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L-Proline hydroxylase is a member of the non-heme Fe2+/α-ketoglutarate (AKG)-dependent hydroxylase family that catalyzes the reaction from L-proline to hydroxy-L-proline, which is widely used in drug synthesis, biochemistry, food supplementation and cosmetic industries. Here, the first crystal structure of L-proline trans-hydroxylase and its complexes with substrate and product are reported, which reveal the structural basis of trans–cis proline hydroxylation selectivity. Structure comparison with other AKG-dependent hydroxylases identifies conserved amino acid residues, which may serve as signatures of in-line or off-line AKG binding modes in the AKG-dependent enzyme family.

Summary A novel concept is described here that utilizes externally applied heat to a solid rod of reconstituted tobacco biomass to form a stream of aerosol under progressively oxygen-deficient atmosphere. The boundary of auto-ignition was determined at oxygen concentrations of 0%, 5%, 10%, and 21% and then the effects of these different atmospheres on various parameters were studied. Experimental results indicated that the ignition temperature decreased with the increase of oxygen concentration and a negative temperature coefficient (NTC) for atmosphere with oxygen was observed at before but close to ignition temperature. Significant differences in the yields of CO and CO2 between oxygen and oxygen-free atmosphere were observed. The mass of aerosol produced under an inert atmosphere and reduced-oxygen atmosphere were characterized with selected volatile and semi-volatile components, phenols, aldehydes, and other organic compounds of interests. In addition, higher oxygen concentration resulted in higher bulk and surface oxygen content of solid-phase residue, the reduction of carbon and hydrogen element content and related functional groups, and the content of inorganic compounds also exhibited an increase with oxygen concentration. By systematically changing oxygen concentrations of the biomass bed with increasing temperatures, an aerosol stream of controlled chemical composition and yields could be formed without leading to ignition. Key chemical markers of inhalation harm were measured and compared to each other under different degrees close to combustion. Studying reconstituted tobacco or other biomass materials in such a way could provide alternative and useful information in the design heated biomass aerosol generators.

Current resolved structures of GPCRs and G protein complexes provided important insights into G protein activation. However, the binding or dissociation of GPCRs with G protein is instantaneous and highly dynamic in the intracellular environment. The conformational dynamic of G protein still needs to be addressed. In this study, we applied 19F solution NMR spectroscopy to monitor the conformational changes of G protein upon interact with detergent mimicking membrane and receptor. Our results show that there are two states equilibria in the Gα in apo states. The interaction of Gα with detergents will accelerate this conformational transformation and induce a state that tends to bind to GPCRs. Finally, the Gα proteins presented a fully activation state when they coupled to GPCRs.

Stress granules (SGs) are cytoplasmic biomolecular condensates containing proteins and RNAs in response to stress. Ras-GTPase–activating protein binding protein 1 (G3BP1) is a core SG protein. Caprin-1 and ubiquitin specific peptidase 10 (USP10) interact with G3BP1, facilitating and suppressing SG formation, respectively. The crystal structures of the nuclear transport factor 2-like (NTF2L) domain of G3BP1 in complex with the G3BP1-interacting motif (GIM) of Caprin-1 and USP10 show that both GIMs bind to the same hydrophobic pocket of G3BP1. Moreover, both GIMs suppressed the liquid–liquid phase separation (LLPS) of G3BP1, suggesting that Caprin-1 likely facilitates SG formation via other mechanisms. Thus, we dissected various domains of Caprin-1 and investigated their role in LLPS in vitro and SG formation in cells. The C-terminal domain of Caprin-1 underwent spontaneous LLPS, whereas the N-terminal domain and GIM of Caprin-1 suppressed LLPS of G3BP1. The opposing effect of the N- and C-terminal domains of Caprin-1 on SG formation were demonstrated in cells with or without the endogenous Caprin-1. We propose that the N- and C-terminal domains of Caprin-1 regulate SG formation in a “yin and yang” fashion, mediating the dynamic and reversible assembly of SGs.

Citral essential oil (CEO) was encapsulated by the single coalescence method, and its stability, release properties, and ability to maintain freshness were evaluated for the first time. The microshape characteristics of a CEO-loaded microcapsule (CM) were analyzed by inverted microscopy (OM) and scanning electron microscopy (SEM). The encapsulation efficiency, stability, and release behavior of CEO were evaluated using Fourier transform infrared spectroscopy (FTIR), thermogravimetric/differential thermal comprehensive analysis (TG/DSC), and gas chromatography mass spectrometry (GC/MS). Moreover, peaches were used to evaluate the preservation properties of the CEO-loaded microcapsule. The results showed that the microcapsule produced using simple coacervation had better microstructure and the ability to reduce and control the release of citral essential oil. The qualities of peaches, such as appearance changes, hardness, soluble solid content, total acids, and total bacterial counts, were significantly improved in the CM system during storage, in comparison with the control and cold storage groups. Therefore, the CM has potential applications and development prospects in the food, drug, and other industries.

Photosystem I (PSI) is a very large membrane protein complex (∼1000 kDa) harboring P700*, the strongest reductant known in biological systems, which is responsible for driving NAD(P)+ and ultimatel...

Iron phosphate-modified pollen microspheres (pollen@FePO4) were prepared and applied as sorbents for the removal of heavy metals (Cd2+ and Pb2+) from the aqueous solution. Batch sorption studies were conducted to investigate the effects of solution pH, contact time, sorbent dosage, and metal concentration on the adsorption process. The sorption of Cd2+ and Pb2+ ions on pollen@FePO4 corresponds to the pseudo-second-order model and Langmuir isotherm, which is similar to the unmodified pollen. At pH 5.92, pollen@FePO4 offers maximum adsorption capacities of 4.623 and 61.35 mg·g−1 for Cd2+ and Pb2+, respectively. The faster sorption kinetics and higher adsorption capacities of Cd2+ and Pb2+ ions onto pollen@FePO4 than pollen indicates that it might be a promising material for the removal of heavy metal ions in aqueous solutions. The possible adsorption mechanism involves electrostatic and chemisorption for Cd2+ and mainly complexion for Pb2+.

Iron phosphates have rich chemical structures with various morphologies and sizes. Since they are environment friendly with good biocompatibility, they have good performances in the fields of catalysis and battery electrode material rising in recent years, as well as in the traditional fields like agriculture and steel. They also have important applications in adsorption, separation and concentration due to their unique structural characteristics. In this paper, iron phosphates are classified based on their common characteristics such as structure, morphology and size, and their application in the past two decades is reviewed, with emphasis on their application in adsorption, separation and concentration of different species. Further, their application in adsorption, separation and concentration of heavy metals is prospected.

5-ALA is the precursor of all tetrapyrroles. 5-Aminolevulinate synthase (ALAS) catalyzes the production of 5-aminolevulinic acid (5-ALA) from glycine and succinyl-CoA. HemA from Rhodopseudomonas palustris (Rp-HemA) was reported to be a highly active ALAS. To understand the catalytic mechanism of Rp-HemA, the 2.05 Å resolution crystal structure of Rp-HemA was solved. Open, half close and close conformations were observed in the substrate-free structures. Structure comparison and sequence alignment suggest the newly observed half close conformation may also be conserved in ALAS family. The pre-existed close and half close conformations in Rp-HemA may play a key role for its high activity.

To understand how the RuvC catalytic domain of Class 2 Cas proteins cleaves DNA, it will be necessary to elucidate the structures of RuvC-containing Cas complexes in their catalytically competent states. Cas12i2 is a Class 2 type V-I CRISPR-Cas endonuclease that cleaves target dsDNA by an unknown mechanism. Here, we report structures of Cas12i2–crRNA–DNA complexes and a Cas12i2–crRNA complex. We reveal the mechanism of DNA recognition and cleavage by Cas12i2, and activation of the RuvC catalytic pocket induced by a conformational change of the Helical-II domain. The seed region (nucleotides 1–8) is dispensable for RuvC activation, but the duplex of the central spacer (nucleotides 9–15) is required. We captured the catalytic state of Cas12i2, with both metal ions and the ssDNA substrate bound in the RuvC catalytic pocket. Together, our studies provide significant insights into the DNA cleavage mechanism by RuvC-containing Cas proteins., Cas12i, class 2 type V CRISPR-Cas system protein, uses a single RuvC domain for cleavage of both strands of target DNA. Structures of Cas12i2–crRNA–DNA complexes not only provide insight into the mechanism of DNA recognition and cleavage by Cas12i2, but also the DNA cleavage mechanism by RuvC-containing Cas proteins.

Light-oxygen-voltage (LOV) proteins are ubiquitous photoreceptors that can interact with other regulatory proteins and then mediate their activities, which results in cellular adaptation and subsequent physiological changes. Upon blue-light irradiation, a conserved cysteine (Cys) residue in LOV covalently binds to flavin to form a flavin-Cys adduct, which triggers a subsequent cascade of signal transduction and reactions. We found a group of natural Cys-less LOV-like proteins in magnetotactic bacteria (MTB) and investigated its physiological functions by conducting research on one of these unusual LOV-like proteins, Amb2291, in Magnetospirillum magneticum. In-frame deletion of amb2291 or site-directive substitution of alanine-399 for Cys mutants impaired the protective responses against hydrogen peroxide, thereby causing stress and growth impairment. Consequently, gene expression and magnetosome formation were affected, which led to high sensitivity to oxidative damage and defective phototactic behaviour. The purified wild-type and A399C-mutated LOV-like proteins had similar LOV blue-light response spectra, but Amb2291A399C exhibited a faster reaction to blue light. We especially showed that LOV-like protein Amb2291 plays a role in magnetosome synthesis and resistance to oxidative stress of AMB-1 when this bacterium was exposed to red light and hydrogen peroxide. This finding expands our knowledge of the physiological function of this widely distributed group of photoreceptors and deepens our understanding of the photoresponse of MTB. KEY POINTS: • We found a group of Cys-less light-oxygen-voltage (LOV) photoreceptors in magnetotactic bacteria, which prompted us to study the light-response and biological roles of these proteins in these non-photosynthetic bacteria. • The Cys-less LOV-like protein participates in the light-regulated signalling pathway and improves resistance to oxidative damage and magnetic crystal biogenesis in Magnetospirillum magneticum. • This result will contribute to our understanding of the structural and functional diversity of the LOV-like photoreceptor and help us understand the complexity of light-regulated model organisms.

Structural and in vivo functional analyses reveal a possible protein secretion tube across the mycobacterial outer envelope., Tuberculosis-causing mycobacteria have thick cell-wall and capsule layers that are formed from complex structures. Protein secretion across these barriers depends on a specialized protein secretion system, but none has been reported. We show that Mycobacterium tuberculosis Rv3705c and its homologous MSMEG_6251 in Mycobacterium smegmatis are tube-forming proteins in the mycobacterial envelope (TiME). Crystallographic and cryo-EM structures of these two proteins show that both proteins form rotationally symmetric rings. Two layers of TiME rings pack together in a tail-to-tail manner into a ring-shaped complex, which, in turn, stacks together to form tubes. M. smegmatis TiME was detected mainly in the cell wall and capsule. Knocking out the TiME gene markedly decreased the amount of secreted protein in the M. smegmatis culture medium, and expression of this gene in knocked-out strain partially restored the level of secreted protein. Our structure and functional data thus suggest that TiME forms a protein transport tube across the mycobacterial outer envelope.

In order to understand the effects of the major algal components-carbohydrates and proteins on the hydrothermal liquefaction (HTL) process of algae, the HTL of polysaccharides or proteins with lipids was performed at 220, 260, 300 °C, respectively. Bio-oil yields and qualities were investigated and compared with the individual liquefaction of the major algal components. Results show that the presence of polysaccharides or proteins has little effect on bio-oil yield but increased the HHV and significantly changed the boiling point distribution as compared with the HTL of lipids. The compositions of bio-oils from the HTL of binary mixtures were similar to that from the HTL of lipids. Heavy components in bio-oil were increased in the presence of polysaccharides or proteins, which was mainly caused by the hydrolysis product of polysaccharides/proteins being easily polymerized during the HTL process, forming macromolecular compounds into bio-oil.

Most identification methods for marine oil spills rely on single-dimensional chemical fingerprinting that is ineffective for weathered oil. A quantitative identification method is proposed in this study based upon multi-dimensional chemical fingerprinting composed of diagnostic ratios, wavelet coefficient, and the Ni/V. Twenty oil samples were used including 6 marine fuels, 7 Middle Eastern crude oils, and 7 non-Middle East crude oils. Diagnostic ratios were discussed using partial least square analysis, and fluorescence spectra were analyzed by db7 wavelet basis of 6-layers in the discrete wavelet transform. The first principal component and the wavelet coefficient at 354 �� 2 nm were combined with Ni/V and optimized by an exhaustive method as variables to establish the Fisher discriminant model. The developed model had 100% accuracy for modeled oil samples and for non-modeled crude oil before and after weathering, respectively, with 83.3% accuracy for non-modeled or short-term weathered marine fuel. The accuracy was 3% higher than reported in the literature.

The relationships between spatial production, urbanization and sustainable development are becoming a focus of the international academic cycle. Urbanization dominated by spatial production driven by capital and power often produces and enlarges uneven development, which leads to multiple eco-environmental problems. Thus, the key to development lies in whether the pattern of urbanization is in harmony with the ecological environment. However, previous researches mainly concentrate on spatial production in developed countries or regions. The urbanization and sustainable development of less-developed regions, with complex and fragile ecological environments, are often overlooked. It is a new idea to explain the relationships and interactions between spatial production, urbanization and sustainable development based on less-developed regions by the theory of spatial production. The paper chooses the Hexi Corridor as a typical case, puts forward a conceptual framework and explores the process of spatial production from 2000 to 2017. The results reveal that urbanization in the Hexi Corridor is a multidimensional socio-spatial process: power and capital gave birth to a higher urbanization and accelerated the process of urbanization, however, the urban-rural gap between regions has not narrowed accordingly. Driven by comprehensive interests, local governments often take some extreme measures to forcefully promote the urbanization process, thereby violating the goals and requirements of sustainable development. At present, there is an urgent need to coordinate the relationship between urban and rural regions on different scales and transform the urbanization model from traditional spatial production to a new-type of urbanization with people-oriented and sustainable development.

Akkermansia muciniphila is a beneficial microorganism colonized in the human gut that can reverse many intestinal metabolic-related diseases. Amuc_1100 is an outer-membrane protein of A. muciniphila. Oral administration of Amuc_1100 can reduce fat mass development, insulin resistance, and dyslipidemia in mice and activated the toll-like receptor 2 (TLR2) to regulate the immune response of the host, but the molecular mechanism remains unclear. Here we report the crystal structure of the extramembranous domain of Amuc_1100, which consists of a four-stranded antiparallel β-sheet and four α-helices. Two C-terminal helices and the four-stranded antiparallel β-sheet formed two "αββ" motifs and constituted the core domain, which shared a similar fold with type IV pili and type II Secretion system protein. Although the full-length of the extramembranous domain of Amuc_1100 existed as a monomer in solution, they formed trimer in the crystal. Elimination of the N-terminal coiled-coil helix α1 led to dimerization of Amuc_1100 both in solution and in crystal, indicating that the oligomeric state of Amuc_1100 was variable and could be influenced by α1. In addition, we identified that Amuc_1100 could directly bind human TLR2 (hTRL2) in vitro, suggesting that Amuc_1100 may serve as a new ligand for hTLR2. Dimerization of Amuc_1100 improved its hTLR2-binding affinity, suggesting that the α1-truncated Amuc_1100 could be a beneficial candidate for the development of A. muciniphila related drugs.

LXYL-P1-2 is one of the few xylosidases that efficiently catalyze the reaction from 7-β-xylosyl-10-deacetyltaxol (XDT) to 10-deacetyltaxol (DT), and is a potential enzyme used in Taxol industrial production. Here we report the crystal structure of LXYL-P1-2 and its XDT binding complex. These structures reveal an enzyme/product complex with the sugar conformation different from the enzyme/substrate complex reported previously in GH3 enzymes, even in the whole glycohydrolases family. In addition, the DT binding pocket is identified as the structural basis for the substrate specificity. Further structure analysis reveals common features in LXYL-P1-2 and Taxol binding protein tubulin, which might provide useful information for designing new Taxol carrier proteins for drug delivery., Yang, Chen et al. report crystallographic structures of GH3 beta-glucosidase LXYL-P1-2 that converts XDT into DT, a precursor for an anticancer drug taxol, and the complex of LXYL-P1-2 with XDT. This study provides insight into the catalytic mechanism for GH3 enzymes.

Photosensitizers, which harness light energy to upgrade weak reductants to strong reductants, are pivotal components of the natural and artificial photosynthesis machineries. However, it has proved difficult to enhance and expand their functions through genetic engineering. Here we report a genetically encoded, 27 kDa photosensitizer protein (PSP), which facilitates the rational design of miniature photocatalytic CO2-reducing enzymes. Visible light drives PSP efficiently into a long-lived triplet excited state (PSP*), which reacts rapidly with reduced nicotinamide adenine dinucleotide to generate a super-reducing radical (PSP•), which is strong enough to reduce many CO2-reducing catalysts. We determined the three-dimensional structure of PSP• at 1.8 A resolution by X-ray crystallography. Genetic engineering enabled the site-specific attachment of a nickel–terpyridine complex and the modular optimization of the photochemical properties of PSP, the chromophore/catalytic centre distance and the catalytic centre microenvironment, which culminated in a miniature photocatalytic CO2-reducing enzyme that has a CO2/CO conversion quantum efficiency of 2.6%. A 27 kDa photosensitizer protein (PSP) has now been developed and used to design a miniature photocatalytic CO2-reducing enzyme. Visible light drives the PSP efficiently to the long-lived triplet excited state (PSP*), and then to a super-reducing radical (PSP•), which is strong enough to reduce many CO2-reducing catalysts. The 3D structure of PSP• at 1.8 A resolution was determined by X-ray crystallography.

Fluorescent proteins (FPs) with emission wavelengths in the far-red and infrared regions of the spectrum provide powerful tools for deep-tissue and super-resolution imaging. The development of red-shifted FPs has evoked widespread interest and continuous engineering efforts. In this article, based on a computational design and genetic code expansion, we report a rational approach to significantly expand and red-shift the chromophore of green fluorescent protein (GFP). We applied computational calculations to predict the excitation and emission wavelengths of a FP chromophore harboring unnatural amino acids (UAA) and identify in silico an appropriate UAA, 2-amino-3-(6-hydroxynaphthalen-2-yl)propanoic acid (naphthol-Ala). Our methodology allowed us to formulate a GFP variant (cpsfGFP-66-Naphthol-Ala) with red-shifted absorbance and emission spectral maxima exceeding 60 and 130 nm, respectively, compared to those of GFP. The GFP chromophore is formed through autocatalytic post-translational modification to generate a planar 4-(p-hydroxybenzylidene)-5-imidazolinone chromophore. We solved the crystal structure of cpsfGFP-66-naphthol-Ala at 1.3 Å resolution and demonstrated the formation of a much larger conjugated π-system when the phenol group is replaced by naphthol. These results explain the significant red-shifting of the excitation and emission spectra of cpsfGFP-66-naphthol-Ala. Graphical abstract

Superparamagnetic Fe3O4@FePO4 nanoparticles with core shell structure were prepared by coating iron phosphate on the surface of Fe3O4 nanoparticles by liquid phase deposition method. The prepared materials were characterized by vibrating sample magnetometer, scanning electron microscopy, X-ray diffractometer, Fourier transform infrared spectrometer, nano Zetasizer, X-ray photoelectron spectroscopy and Raman spectrometer. These characterization methods were also used to describe the adsorption mechanism. The obtained composite material was used for the adsorption of a heavy metal element, cadmium. Its unique magnetic properties are favorable for rapid separation and preconcentration of trace cadmium from aqueous solutions. About 100% sorption was achieved at pH 7 for 1mL, 10μgL-1 of cadmium. Batch adsorption experiments show that the adsorption fits Langmuir model, and a maximum adsorption capacity 13.51mgg-1 is derived for Cd(II). The retained Cd(II) could be readily recovered by 200μL of HNO3 (0.01molL-1). The cadmium in the eluate is quantified with detection by electrothermal atomic absorption spectrometry (ETAAS). A sample volume of 2000μL creates an enrichment factor of 10.3, along with a detection limit of 0.021µgL-1 (3σ, n=7) and a RSD of 1.3% (0.1µgL-1, n=7) within a linear calibration range of 0.05-0.5µgL-1. The practical applicability of this procedure was validated by analyzing cadmium contents in a certified reference material (GBW08608) and two environmental water samples.

Summary SUN proteins are the core components of LINC complexes that span across the nuclear envelope for nuclear positioning and migration. SUN proteins contain at least one predicted coiled-coil domain preceding the SUN domain. Here, we found that the two coiled-coil domains (CC1 and CC2) of SUN2 exhibit distinct oligomeric states. CC2 is a monomer in solution. The structure of the CC2-SUN monomer revealed that CC2 unexpectedly folds as a three-helix bundle that interacts with the SUN domain and locks it in an inactive conformation. In contrast, CC1 is a trimer. The structure of the CC1 trimer demonstrated that CC1 is an imperfect coiled coil for the trimerization and activation of the SUN domain. Modulations of CC1 and CC2 dictate different oligomeric states of CC1-CC2-SUN, which is essential for LINC complex formation. Thus, the two coiled-coil domains of SUN2 act as the intrinsic dynamic regulators for controlling the SUN domain activity.

The signaling of prostaglandin D(2) (PGD(2)) through a G protein-coupled receptor (GPCR), CRTH2, is a major pathway in type 2 inflammation. Compelling evidence suggests the therapeutic benefits of blocking CRTH2 signaling in many inflammatory disorders. Currently, a number of CRTH2 antagonists are under clinical investigation and one compound, fevipiprant, has advanced to phase 3 clinical trials for asthma. Here, we present the crystal structures of human CRTH2 with two antagonists, fevipiprant and CAY10471. The structures, together with docking and ligand binding data, reveal a semioccluded pocket covered by a well-structured amino terminus and different binding modes of chemically diverse CRTH2 antagonists. Structural analysis suggests a ligand entry port and a binding process that is facilitated by opposite charge attraction for PGD(2), which differs significantly from the binding pose and binding environment of lysophospholipids and endocannabinoids, revealing a new mechanism for lipid recognition by GPCRs.

Photosensitizers, which harness light energy to upgrade weak reductants to strong reductants, are pivotal components of the natural and artificial photosynthesis machineries. However, it has proved difficult to enhance and expand their functions through genetic engineering. Here we report a genetically encoded, 27 kDa photosensitizer protein (PSP), which facilitates the rational design of miniature photocatalytic CO

The accurate modification of the tRNAIle anticodon wobble cytosine 34 is critical for AUA decoding in protein synthesis. Archaeal tRNAIle2 cytosine 34 is modified with agmatine in the presence of ATP by TiaS (tRNAIle2 agmatidine synthetase). However, no structure of apo-form full-length TiaS is available currently. Here, the crystal structures of apo TiaS and a complex of TiaS-agmatine-AMPPCP-Mg are presented, with properly folded zinc ribbon and Cys4-zinc coordination identified. Compared with tRNAIle2-bound form, the architecture of apo TiaS shows a totally different conformation of zinc ribbon. Molecular dynamics simulations of the docking complex between free-state TiaS and tRNAIle2 suggest that zinc ribbon domain is capable of performing large-scale motions to sample substrate binding-competent conformation. Principle component analysis and normal mode analysis show consistent results about the relative directionality of functionally correlated zinc ribbon motions. Apo TiaS and TiaS-agmatine-AMPPCP-Mg/TiaS-AMPCPP-Mg complex structures capture two snapshots of the flexible ATP-Mg binding p2loop step-by-step stabilization. Research from this study provides new insight into TiaS functional mechanism and the dynamic feature of zinc ribbons.

Adaptations to hypoxia play an important role inMycobacterium tuberculosispathogenesis. Rv0324, which contains an HTH DNA-binding domain and a rhodanese domain, is one of the key transcription regulators in response to hypoxia.M. tuberculosisRv1674c is a homologue of Rv0324. To understand the interdomain interaction and regulation of the HTH domain and the rhodanese domain, recombinant Rv1674c protein was purified and crystallized by the vapour-diffusion method. The crystals diffracted to 2.25 Å resolution. Preliminary diffraction analysis suggests that the crystals belonged to space groupP3121 orP3221, with unit-cell parametersa=b= 67.8,c= 174.5 Å, α = β = 90, γ = 120°. The Matthews coefficient was calculated to be 2.44 Å3 Da−1, assuming that the crystallographic asymmetric unit contains two protein molecules.

While nature employs various covalent and non-covalent strategies to modulate tyrosine (Y) redox potential and pKa to optimize enzyme activities, such approaches have not been systematically applied for the design of functional metalloproteins. Through the genetic incorporation of 3-methoxytyrosine (OMeY) into myoglobin, we recapitulated important features of cytochrome c oxidase (CcO) into this small soluble protein, which exhibits selective O2 reduction activity while generating small amount of reactive oxygen species (ROS). These results demonstrate that the electron donating ability of a tyrosine residue in the active site is important for CcO function. Moreover, we elucidated the structural basis for the genetic incorporation of OMeY into proteins, by solving the X-ray structure of OMeY specific aminoacyl-tRNA synthetase in complex with OMeY.

The preferred drugs for the treatment of syphilis, benzathine and procaine penicillin, have not been available in Shanghai for many years, and currently, the incidence of syphilis is increasing. Alternative antibiotics for patients with syphilis during the benzathine and procaine penicillin shortage include macrolides. The failure of macrolide treatment in syphilis patients has been reported in Shanghai, but the reason for this treatment failure remains unclear. We used polymerase chain reaction technology to detect a 23S rRNA A2058G mutation in Treponema pallidum in 109 specimens from syphilis patients. The use of azithromycin/erythromycin in the syphilis patients and the physicians' prescription habits were also assessed based on two questionnaires regarding the use of macrolides. A total of 104 specimens (95.4%) were positive for the A2058G mutation in both copies of the 23S rRNA gene, indicating macrolide resistance. A questionnaire provided to 122 dermatologists showed that during the penicillin shortage, they prescribed erythromycin and azithromycin for 8.24±13.95% and 3.21±6.37% of their patients, respectively, and in the case of penicillin allergy, erythromycin and azithromycin were prescribed 15.24±22.89% and 7.23±16.60% of the time, respectively. A second questionnaire provided to the syphilis patients showed that 150 (33.7%), 106 (23.8%) and 34 (7.6%) individuals had used azithromycin, erythromycin or both, respectively, although the majority did not use the drugs for syphilis treatment. Our findings suggest that macrolide resistance in Treponema pallidum is widespread in Shanghai. More than half of the syphilis patients had a history of macrolide use for other treatment purposes, which may have led to the high prevalence of macrolide resistance. Physicians in China are advised to not use azithromycin for early syphilis.

Superparamagnetic Fe