Search

Background: Sodium oligomannate was approved for marketing by the National Medical Products Administration of China in 2019 for improving cognitive functions in mild-to-moderate Alzheimer's disease patients. Method: LC–MS/MS methods were established and validated for the quantitation of sodium oligomannate in human plasma, urine and feces to support clinical development studies. Samples were prepared using liquid–liquid extraction and analyzed by ion-pair reversed-phase LC–MS/MS with calibration standard curve ranges of 25.0–5000 ng/ml, 0.500–100 μg/ml and 100–10,000 μg/g in plasma, urine and feces, respectively. Results & conclusion: All validation parameters met the respective acceptance criteria established by US FDA and International Council for Harmonisation of Technical Requirements for Human Use guidelines. The validated methods were applied to a pharmacokinetics and excretion study in healthy Chinese subjects.

Chromokinesins NOD and KID have similar DNA binding domains and functions during cell division, while their motor domain sequences show significant variations. It has been unclear whether these motors have similar structure, chemistry, and microtubule interactions necessary to follow a similar mechanism of force mediation. We used biochemical rate measurements, cosedimentation, and structural analysis to investigate the ATPase mechanisms of the NOD and KID core domains. These experiments and analysis revealed that NOD and KID have different ATPase mechanisms, microtubule interactions, and catalytic domain structures. The ATPase cycles of NOD and KID have different rate limiting steps. The ATPase rate of NOD was robustly stimulated by microtubules albeit its microtubule affinity was weakened in all nucleotide bound states. KID bound microtubules tightly in all nucleotide states and remained associated with the microtubule for more than 100 cycles of ATP hydrolysis before dissociating. The structure of KID was most similar to conventional kinesin (KIF5). Key differences in the microtubule binding region and allosteric communication pathway between KID and NOD are consistent with our biochemical data. Our results support the model that NOD and KID utilize distinct mechanistic pathways to achieve the same function during cell division.

An emerging technology, three-dimensional (3D) cadastres as extensions to the current parcel-based or two-dimensional (2D) cadastre, has been developed to meet the management of 3D urban land use and 3D properties. This chapter provides a brief review of the key issues of 3D cadastre and the spatial representation of ownership. In order to understand the importance of legislation for developing modeling technology for 3D property, the legislative context of ownership is addressed in specific reference to China. In light of spatial rights of land-use space, a 3D spatial model of property is presented in terms of polyhedra with four-layer structures. Being compatible with the existing 2D cadastre, this 3D spatial data structure is suitable as a hybrid cadastral system for 2D and 3D property and provides an available means to spatially represent 3D property with integrity. By analyzing the heterogeneity of the land space used for property, the ownership of condominiums with internal structure is addressed and spatial representation of ownership is presented by instantiation in a case study in China.

Herein we disclose SAR studies of a series of dimethylamino pyrrolidines which we recently reported as novel inhibitors of the PRC2 complex through disruption of EED/H3K27me3 binding. Modification of the indole and benzyl moieties of screening hit 1 provided analogs with substantially improved binding and cellular activities. This work culminated in the identification of compound 2, our nanomolar proof-of-concept (PoC) inhibitor which provided on-target tumor growth inhibition in a mouse xenograft model. X-ray crystal structures of several inhibitors bound in the EED active-site are also discussed.

The high proliferation rate of tumor cells demands high energy and metabolites that are sustained by a high glycolytic flux known as the ‘Warburg effect’. The activation and further metabolism of glucose is initiated by hexokinase, a focal point of metabolic regulation. The human hexokinase 2 (HK2) is overexpressed in all aggressive tumors and predominantly found on the outer mitochondrial membrane, where interactions through its N-terminus initiates and maintains tumorigenesis. Here, we report the structure of HK2 in complex with glucose and glucose-6-phosphate (G6P). Structural and biochemical characterization of the mitochondrial conformation reveals higher conformational stability and slow protein unfolding rate (ku) compared with the cytosolic conformation. Despite the active site similarity of all human hexokinases, the N-domain of HK2 is catalytically active but not in hexokinase 1 and 3. Helix-α13 that protrudes out of the N-domain to link it to the C-domain of HK2 is found to be important in maintaining the catalytic activity of the N-half. In addition, the N-domain of HK2 regulates the stability of the whole enzyme in contrast with the C-domain. Glucose binding enhanced the stability of the wild-type (WT) enzyme and the single mutant D657A of the C-domain, but it did not increase the stability of the D209A mutant of the N-domain. The interaction of HK2 with the mitochondria through its N-half is proposed to facilitate higher stability on the mitochondria. The identification of structural and biochemical differences between HK2 and other human hexokinase isozymes could potentially be used in the development of new anticancer therapies.

Kinesin microtubule motor proteins play essential roles in division, including attaching chromosomes to spindles and crosslinking microtubules for spindle assembly. Human kinesin-14 KIFC1 is unique in that cancer cells with amplified centrosomes are dependent on the motor for viable division because of its ability to cluster centrosomes and form bipolar spindles, but it is not required for division in almost all normal cells. Screens for small molecule inhibitors of KIFC1 have yielded several candidates for further development, but obtaining structural data to determine their sites of binding has been difficult. Here we compare a previously unreported KIFC1 crystal structure with new structures of two closely related kinesin-14 proteins, Ncd and KIFC3, to determine the potential binding site of a known KIFC1 ATPase inhibitor, AZ82. We analyze the previously identified kinesin inhibitor binding sites and identify features of AZ82 that favor binding to one of the sites, the α4/α6 site. This selectivity can be explained by unique structural features of the KIFC1 α4/α6 binding site. These features may help improve the drug-like properties of AZ82 and other specific KIFC1 inhibitors.

To investigate the role played by the unique pre-DFG residue Val 195 of Cdc7 kinase on the potency of azaindole-chloropyridines (1), a series of novel analogues with various chloro replacements were synthesized and evaluated for their inhibitory activity against Cdc7. X-ray cocrystallization using a surrogate protein, GSK3β, and modeling studies confirmed the azaindole motif as the hinge binder. Weaker hydrophobic interactions with Met 134 and Val 195 by certain chloro replacements (e.g., H, methyl) led to reduced Cdc7 inhibition. Meanwhile, data from other replacements (e.g., F, O) indicated that loss of such hydrophobic interaction could be compensated by enhanced hydrogen bonding to Lys 90. Our findings not only provide an in-depth understanding of the pre-DFG residue as another viable position impacting kinase inhibition, they also expand the existing knowledge of ligand-Cdc7 binding.

Polycomb repressive complex 2 (PRC2) is a regulator of epigenetic states required for development and homeostasis. PRC2 trimethylates histone H3 at lysine 27 (H3K27me3), which leads to gene silencing, and is dysregulated in many cancers. The embryonic ectoderm development (EED) protein is an essential subunit of PRC2 that has both a scaffolding function and an H3K27me3-binding function. Here we report the identification of A-395, a potent antagonist of the H3K27me3 binding functions of EED. Structural studies demonstrate that A-395 binds to EED in the H3K27me3-binding pocket, thereby preventing allosteric activation of the catalytic activity of PRC2. Phenotypic effects observed in vitro and in vivo are similar to those of known PRC2 enzymatic inhibitors; however, A-395 retains potent activity against cell lines resistant to the catalytic inhibitors. A-395 represents a first-in-class antagonist of PRC2 protein-protein interactions (PPI) for use as a chemical probe to investigate the roles of EED-containing protein complexes.

Isothermal calorimetric studies of the binding of iron(III) citrate to ferric ion binding protein from Neisseria gonorrhoeae suggested the complexation of a tetranuclear iron(III) cluster as a single step binding event (apparent binding constant K(app) (ITC) = 6.0(5) × 10(5) M(-1)). High-resolution Fourier transform ion cyclotron resonance mass spectrometric data supported the binding of a tetranuclear oxo(hydroxo) iron(III) cluster of formula [Fe(4)O(2)(OH)(4)(H(2)O)(cit)](+) in the interdomain binding cleft of FbpA. The mutant H9Y-nFbpA showed a twofold increase in the apparent binding constant [K(app) (ITC) = 1.1(7) × 10(6) M(-1)] for the tetranuclear iron(III) cluster compared to the wild-type protein. Mössbauer spectra of Escherichia coli cells overexpressing FbpA and cultured in the presence of added (57)Fe citrate were indicative of the presence of dinuclear and polynuclear clusters. FbpA therefore appears to have a strong affinity for iron clusters in iron-rich environments, a property which might endow the protein with new biological functions.

The MBT repeat has been recently identified as a key domain capable of methyl-lysine histone recognition. Functional work has pointed to a role for MBT domain-containing proteins in transcriptional repression of developmental control genes such as Hox genes. In this study, L3MBTL2, a human homolog of Drosophila Sfmbt critical for Hox gene silencing, is demonstrated to preferentially recognize lower methylation states of several histone-derived peptides through its fourth MBT repeat. High-resolution crystallographic analysis of the four MBT repeats of this protein reveals its unique asymmetric rhomboid architecture, as well as binding mechanism, which preclude the interaction of the first three MBT repeats with methylated peptides. Structural elucidation of an L3MBTL2-H4K20me1 complex and comparison with other MBT-histone peptide complexes also suggests that an absence of distinct surface contours surrounding the methyl-lysine-binding pocket may underlie the lack of sequence specificity observed for members of this protein family.

Streptococcus pneumoniae endo-alpha-N-acetylgalactosaminidase is a cell surface-anchored glycoside hydrolase from family GH101 involved in the breakdown of mucin type O-linked glycans. The 189-kDa mature enzyme specifically hydrolyzes the T-antigen disaccharide from extracellular host glycoproteins and is representative of a broadly important class of virulence factors that have remained structurally uncharacterized due to their large size and highly modular nature. Here we report a 2.9 angstroms resolution crystal structure that remarkably captures the multidomain architecture and characterizes a catalytic center unexpectedly resembling that of alpha-amylases. Our analysis presents a complete model of glycoprotein recognition and provides a basis for the structure-based design of novel Streptococcus vaccines and therapeutics.

Background: Bacterial virulence-associated type III secretion system (T3SS) assembly requires a dedicated enzyme to penetrate peptidoglycan (PG).Results: We structurally characterized a T3SS PG-lytic enzyme, identified catalytically important residues, and characterized its activity.Conclusion: The active site is similar to lysozymes and lytic transglycosylases and interaction with the T3SS enhances activity.Significance: Structural information is critical for development of drugs targeting T3SS PG-lytic enzymes.The Gram-negative bacterium enteropathogenic Escherichia coli uses a syringe-like type III secretion system (T3SS) to inject virulence or “effector” proteins into the cytoplasm of host intestinal epithelial cells. To assemble, the T3SS must traverse both bacterial membranes, as well as the peptidoglycan layer. Peptidoglycan is made of repeating N-acetylmuramic acid and N-acetylglucosamine disaccharides cross-linked by pentapeptides to form a tight mesh barrier. Assembly of many macromolecular machines requires a dedicated peptidoglycan lytic enzyme (PG-lytic enzyme) to locally clear peptidoglycan. Here we have solved the first structure of a T3SS-associated PG-lytic enzyme, EtgA from enteropathogenic E. coli. Unexpectedly, the active site of EtgA has features in common with both lytic transglycosylases and hen egg white lysozyme. Most notably, the β-hairpin region resembles that of lysozyme and contains an aspartate that aligns with lysozyme Asp-52 (a residue critical for catalysis), a conservation not observed in other previously characterized lytic transglycosylase families to which the conserved T3SS enzymes had been presumed to belong. Mutation of the EtgA catalytic glutamate, Glu-42, conserved across lytic transglycosylases and hen egg white lysozyme, and this differentiating aspartate diminishes type III secretion in vivo, supporting its essential role in clearing the peptidoglycan for T3SS assembly. Finally, we show that EtgA forms a 1:1 complex with the building block of the polymerized T3SS inner rod component, EscI, and that this interaction enhances PG-lytic activity of EtgA in vitro, collectively providing the necessary strict localization and regulation of the lytic activity to prevent overall cell lysis.

The four TeII complexes, cis-[TeCl2{(iPrNH)2CS}2] (1), cis-[TeCl2{(iBuNH)2CS}2] (2), trans-[TeCl2{(PhNMe)2CS}2] (3), and trans-[TeCl2{(Et2N)2CS}2] (4), have been synthesised and their molecular structures solved by means of X-ray crystallography. All four complexes are square planar, those with disubstituted thiourea ligands have a cis configuration, those with tetrasubstituted thioureas have a trans configuration. The Te–S bond lengths in 1 and 2 average 2.4994 and 2.5213 A, respectively. The Te–Cl bonds trans to the Te–S bonds have average lengths of 2.8754 and 2.8334 A, reflecting the trans influence of the two disubstituted thioureas. In 3 and 4 with identical ligands trans to each other, the average Te–S and Te–Cl bond lengths are 2.6834 and 2.5964 A, respectively. Cis-trans-Isomerie in quadratisch-planaren [TeCl2(stu)2]-Komplexen mit substituierten, voluminosen Thioharnstoff(stu)-Liganden. Synthesen und Strukturen von vier neuen Tellur(II)-Komplexen Die vier TeII-Komplexe cis-[TeCl2{(iPrNH)2CS}2] (1), cis-[TeCl2{(iBuNH)2CS}2] (2), trans-[TeCl2((PhNMe)2CS}2] (3) und trans-[TeCl2{(Et2N)2CS}2] (4) wurden synthetisiert und ihre Strukturen durch Rontgenkristallstrukturanalysen bestimmt. Die vier Komplexe sind quadratisch-planar, wobei die mit disubstituierten Thioharnstoffliganden eine cis-Konfiguration und die vierfachsubstituierten eine trans-Konfiguration haben. Die Bindungslangen Te–S in 1 bzw. 2 betragen im Mittel 2,4994 bzw. 2,5213 A. Die Te–Cl-Bindungen in trans-Stellung zu den Te–S-Bindungen betragen im Mittel 2,8754 bzw. 2,8334 A, was den trans-Einflus der zwei disubstituierten Thioharnstoffeinheiten widerspiegelt. In 3 und 4 mit identischen Liganden in trans-Stellung zueinander betragen die mittleren Bindungslangen Te–S bzw. Te–Cl 2,6834 bzw. 2,5964 A.

Horse heart cytochrome c and apocytochrome c (with the Fe-porphyrin removed), which have completely different conformations, are selectively cleaved at the same site in the presence of cis-[Pd(dtco-3-OH)(H2O)2]2+ (dtco-3-OH=dithiacycrooctan-3-ol). The cleaved fragments were separated by SDS–polyacrylamide gel electrophoresis and the cleavage yields were determined by a scanning densitometer. The site and size of cleavage were confirmed by precisely determining molecular masses of the proteins and of the cleaved fragments using electrospray mass spectrometry. Different pH behavior in the cleavage of cytochrome c and apocytochrome c is observed due to a requirement of a partially unfolded state II of the cytochrome c. Although the Pd(II) complex coordinates to different sulfur forms of Cys17 in the cytochrome c and the apocytochrome c (thioether in the former and thiolate anion in the latter), their cleavage yields at pH

We tested the general applicability of in situ proteolysis to form protein crystals suitable for structure determination by adding a protease (chymotrypsin or trypsin) digestion step to crystallization trials of 55 bacterial and 14 human proteins that had proven recalcitrant to our best efforts at crystallization or structure determination. This is a work in progress; so far we determined structures of 9 bacterial proteins and the human aminoimidazole ribonucleotide synthetase (AIRS) domain.

Kinesin-1 transports various cargos along the axon by interacting with the cargos through its light chain subunit. Kinesin light chains (KLC) utilize its tetratricopeptide repeat (TPR) domain to interact with over 10 different cargos. Despite a high sequence identity between their TPR domains (87%), KLC1 and KLC2 isoforms exhibit differential binding properties towards some cargos. We determined the structures of human KLC1 and KLC2 tetratricopeptide repeat (TPR) domains using X-ray crystallography and investigated the different mechanisms by which KLCs interact with their cargos. Using isothermal titration calorimetry, we attributed the specific interaction between KLC1 and JNK-interacting protein 1 (JIP1) cargo to residue N343 in the fourth TRP repeat. Structurally, the N343 residue is adjacent to other asparagines and lysines, creating a positively charged polar patch within the groove of the TPR domain. Whereas, KLC2 with the corresponding residue S328 did not interact with JIP1. Based on these finding, we propose that N343 of KLC1 can form "a carboxylate clamp" with its neighboring asparagine to interact with JIP1, similar to that of HSP70/HSP90 organizing protein-1's (HOP1) interaction with heat shock proteins. For the binding of cargos shared by KLC1 and KLC2, we propose a different site located within the groove but not involving N343. We further propose a third binding site on KLC1 which involves a stretch of polar residues along the inter-TPR loops that may form a network of hydrogen bonds to JIP3 and JIP4. Together, these results provide structural insights into possible mechanisms of interaction between KLC TPR domains and various cargo proteins.

A recent survey of protein expression patterns in patients with Alzheimer's disease (AD) has identified ece2 (chromosome: 3; Locations: 3q27.1) as the most significantly downregulated gene within the tested group. ece2 encodes endothelin-converting enzyme ECE2, a metalloprotease with a role in neuropeptide processing. Deficiency in the highly homologous ECE1 has earlier been linked to increased levels of AD-related {beta}-amyloid peptide in mice, consistent with a role for ECE in the degradation of that peptide. Initially, ECE2 was presumed to resemble ECE1, in that it comprises a single transmembrane region of {approx}20 residues flanked by a small amino-terminal cytosolic segment and a carboxy-terminal lumenar peptidase domain. The carboxy-terminal domain has significant sequence similarity to both neutral endopeptidase, for which an X-ray structure has been determined, and Kell blood group protein. After their initial discovery, multiple isoforms of ECE1 and ECE2 were discovered, generated by alternative splicing of multiple exons. The originally described ece2 transcript, RefSeq NM{_}174046, contains the amino-terminal cytosolic portion followed by the transmembrane region and peptidase domain (Fig. 1, isoform B). Another ece2 transcript, available from the Mammalian Gene Collection under MGC2408 (Fig. 1, isoform C), RefSeq accession NM{_}032331, is predicted to be translated into a 255 residue peptidemore » with low but detectable sequence similarity to known S-adenosyl-L-methionine (SAM)-dependent methyltransferases (SAM-MTs), such as the hypothetical protein TT1324 from Thermus thermophilis, PDB code 2GS9, which shares 30% amino acid sequence identity with ECE2 over 138 residues of the sequence. Intriguingly, another 'elongated' ece2 transcript (Fig. 1, isoform A) (RefSeq NM{_}014693) contains an amino-terminal portion of the putative SAM-MT domain, the transmembrane domain, and the protease domain. This suggests the possibility for coexistence of the putative SAM-MT and protease domains in a single polypeptide and their transmembrane interplay. Although sequence conservation across the SAM-MT family is weak, the structural fold is highly conserved. The most conserved part of this fold is the SAM-binding subdomain, which is shared between MGC2408 and hypothetical protein TT1324. Typically, the SAM-binding subdomain is flanked by a variable Nterminal extension and, at the C-terminus, by a substrate- binding subdomain, which varies enormously in size but preserves a conserved topology with three antiparallel b-strands. The 'elongated' transcript of ece2 lacks this substrate-binding subdomain. To test the hypothesis that the 255 residue ece2 gene product MGC2408 represents a complete SAM-MT fold, we have determined a crystal structure of this protein in the presence of SAH.« less

We report a set of three 1.8–1.9 Å resolution X-ray crystal structures of Neisseria gonorrhoeae Fbp (ferric-ion binding protein): (i) open-cleft apo-Fbp containing bound phosphate, (ii) opencleft mono-Fe Fbp capped by nitrilotriacetate, and (iii) open-cleft trinuclear oxo-iron Fbp, the first structure of an iron-cluster adduct of a transferrin. The nine independent molecules in the unit cells provide ‘snapshots’ of the versatile dynamic structural roles of the conserved dityrosyl iron-binding motif (Tyr195-Tyr196) which control the capture and, possibly, processing of iron. These findings have implications for understanding bacterial iron acquisition and dissimilation, and organic/mineral interfaces. Key words: bacterial transferrin, dityrosyl motif, iron-binding protein, iron transport, oxo-iron cluster, X-ray crystallography.

Transferrins transport Fe3+ and other metal ions in mononuclear-binding sites. We present the first evidence that a member of the transferrin superfamily is able to recognize multi-nuclear oxo-metal clusters, small mineral fragments that are the most abundant forms of many metals in the environment. We show that the ferric ion–binding protein from Neisseria gonorrhoeae (nFbp) readily binds clusters of Fe3+, Ti4+, Zr4+ or Hf4+ in solution. The 1.7 A resolution crystal structure of Hf–nFbp reveals three distinct types of clusters in an open, positively charged cleft between two hinged protein domains. A di-tyrosyl cluster nucleation motif (Tyr195-Tyr196) is situated at the bottom of this cleft and binds either a trinuclear oxo-Hf cluster, which is capped by phosphate, or a pentanuclear cluster, which in turn can be capped with phosphate. This first high-resolution structure of a protein–mineral interface suggests a novel metal-uptake mechanism and provides a model for protein-mediated mineralization/dissimilation, which plays a critical role in geochemical processes. NOTE: In the version of this article initially published online, the institution affiliations were assigned incorrectly because of a mistake that occurred during production. The correct affiliations for all authors are as follows: Dmitriy Alexeev1, Haizhong Zhu2, Maolin Guo2,3, Weiqing Zhong2,4, Dominic J.B. Hunter2, Weiping Yang2,3, Dominic J. Campopiano2 and Peter J. Sadler2. All of the footnotes (corrected) are as follows: 1Institute of Cell and Molecular Biology, Michael Swann Building, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK; 2School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, UK; 3Current address: Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, USA; and 4Current address: School of Pharmacy, Second Military Medicine University, Shanghai 200433, China. We apologize for any inconvenience this may have caused. This mistake has been corrected in the HTML and print version of the article.

During the synthesis of a series of square-planar [TeCl2(stu)2] complexes, where stu represents bulky di- or tetrasubstituted thio­ureas, the title compound, [TeCl{(C6H11NH)2CS}3]Cl or C39H72ClN6S3Te+·Cl−, was the unexpected result when stu was N,N′-di­cyclo­hexyl­thio­urea. The complex is square planar, with Te—S distances of 2.5803 (4), 2.6211 (4) and 2.8214 (4) A, and a Te—Cl distance of 2.6485 (4) A, indicating a small trans influence of the thio­urea ligand.

Mycobacterium tuberculosis, the etiological agent of TB, possesses a cholesterol catabolic pathway implicated in pathogenesis. This pathway includes an iron-dependent extradiol dioxygenase, HsaC, that cleaves catechols. Immuno-compromised mice infected with a ΔhsaC mutant of M. tuberculosis H37Rv survived 50% longer than mice infected with the wild-type strain. In guinea pigs, the mutant disseminated more slowly to the spleen, persisted less successfully in the lung, and caused little pathology. These data establish that, while cholesterol metabolism by M. tuberculosis appears to be most important during the chronic stage of infection, it begins much earlier and may contribute to the pathogen's dissemination within the host. Purified HsaC efficiently cleaved the catecholic cholesterol metabolite, DHSA (3,4-dihydroxy-9,10-seconandrost-1,3,5(10)-triene-9,17-dione; k cat/K m = 14.4±0.5 µM−1 s−1), and was inactivated by a halogenated substrate analogue (partition coefficient, Author Summary Mycobacterium tuberculosis, the etiological agent of TB, is the most devastating infectious agent of mortality worldwide: it is carried by one-third of all humans and kills nearly two million people annually. Recent work has established that the pathogen metabolizes cholesterol, although the role of this metabolism in pathogenesis remains unclear. In the current study, we demonstrate that HsaC is a key enzyme in the cholesterol catabolic pathway and that it can be inactivated by compounds that resemble its substrate. Using molecular genetic approaches, we demonstrated that the enzyme is essential for the growth of M. tuberculosis on cholesterol and that a lack of this enzyme impairs the survival of the pathogen in each of two animal models. These studies provide definitive evidence that M. tuberculosis metabolizes cholesterol during infection and that this metabolism occurs during the early stages of infection. The oxygen-utilizing enzymes of the cholesterol catabolic pathway, of which HsaC is but one example, are intriguing potential chemotherapeutic targets, as their inhibition can lead to toxic metabolites, including reactive oxygen species. Overall, our study combines a variety of approaches to provide novel insights into a disease of global importance and into the mechanism of an interesting class of enzymes.

Acknowledgements We thank The Wellcome Trust (Edinburgh Protein Interaction Centre), Darwin Trust (Fellowship for DA), University of Edinburgh and CVCP (scholarship, small project grant for travel to ICBIC11, and ORS Award for HZ) for their support for this work. Aims • Most of the Fe3+ in the environment is present as oxyhydroxide clusters and minerals but no molecular mechanism for the capture of such polymers by bacteria has yet been described. • Here we investigate whether Fbp can capture oxyhydroxide Fe3+ complexes.