Search

Elongation factor P (EF-P) is a translation protein factor that plays an important role in specialized translation of consecutive proline amino acid motifs. EF-P is an essential protein for cell fitness in native environmental conditions. It regulates synthesis of proteins involved in bacterial motility, environmental adaptation and bacterial virulence, thus making EF-P a potential drug target. In the present study, we determined the solution and crystal structure of EF-P from the pathogenic bacteria Staphylococcus aureus at 1.48 Å resolution. The structure can serve as a platform for structure-based drug design of novel antibiotics to combat the growing antibiotic resistance of S. aureus.

Staphylococcus aureus hibernation promoting factor (SaHPF) is a 22,2 kDa protein which plays a crucial role in 100S Staphylococcus aureus ribosome formation during stress. SaHPF consists of N-terminal domain (NTD) that prevents proteins synthesis by binding to the 30S subunit at the P- and A-sites, connected through a flexible linker with a C-terminal domain (CTD) that keeps ribosomes in 100S form via homodimerization. Recently obtained 100S ribosome structure of S. aureus by cryo-EM shown that SaHPF-NTD bound to the ribosome active sites, however due to the absence of SaHPF-NTD structure it was modeled by homology with the E. coli hibernation factors HPF and YfiA. In present paper we have determined the solution structure of SaHPF-NTD by high-resolution NMR spectroscopy which allows us to increase structural knowledge about HPF structure from S. aureus.

Ribosome binding factor A (RbfA) is a 14.9 kDa adaptive protein of cold shock, which is important for bacterial growth at low temperatures. RbfA can bind to the free 30S ribosomal subunit and interacts with the 5'-terminal helix (helix I) of 16S rRNA. RbfA is important for the efficient processing of 16S rRNA and for the maturation (assembly) of 30S ribosomal subunits. Here we report backbone and side chains (1)H, (13)C and (15)N chemical shift assignments of RbfA from Staphylococcus aureus. Analysis of the backbone chemical shifts by TALOS+ suggests that RbfA contains four alpha-helixes and three beta-strands with alpha1-beta1-beta2-alpha2-alpha3-beta3-alpha4 topology. Secondary structure of RbfA have KH-domain fold topology with betaalphaalphabeta subunit which is characterized by a helix-kink-helix motif in which the GxxG sequence is replaced by a conserved AxG sequence, where an Ala residue at position 70 forming an interhelical kink. The solution of the structure of this protein factor and its complex with the ribosome by NMR spectroscopy, X-ray diffraction analysis and cryo-electron microscopy will allow further development of highly selective substances for slowing or completely stopping the translation of the pathogenic bacterium S. aureus, which will interfere with the synthesis and isolation of its pathogenicity factors.

Elongation Factor P (EF-P) is a 20.5 kDa protein that provides specialized translation of special stalling amino acid motifs. Proteins with stalling motifs are often involved in various processes, including stress resistance and virulence. Thus it has been shown that the virulent properties of microorganisms can be significantly reduced if the work of EF-P is disrupted. In order to elucidate the structure, dynamics and function of EF-P from Staphylococcus aureus (S. aureus), here we report backbone and side chains 1H, 13C and 15N chemical shift assignments of EF-P. Analysis of the backbone chemical shifts by TALOS+ suggests that EF-P contains 1 α-helix and 13 β-strands (β1-β2-β3-β4-β5-β6-β7-α1-β8-β9-β10-β11-β12-β13). The solution of the structure of this protein by NMR and X-ray diffraction analysis, as well as the structure of the ribosome complex by cryo-electron microscopy, will allow further screening of highly selective inhibitors of the translation of the pathogenic bacterium S. aureus. Here we report the almost complete 1H, 13C, 15N backbone and side chain NMR assignment of a 20.5 kDa EF-P.

Background: Ribosome biogenesis is a complex process of ribosomal RNA and protein binding. Bacterial ribosome maturation and components involved in it are especially interesting, because they are widespread targets for antibiotics. A number of special protein factors facilitating the maturation of the 30S small ribosomal subunit are known. One of them is a ribosome-binding factor A (RbfA). This is a small (~14 kDa) protein with KH-domain organization distinguishing RNA binding proteins. Recent cryo-EM reconstruction of E.coli 30S-RbfA complex indicates that RbfA binds to 30S subunit on the central decoding region and promotes the switch from the immature state of h28 (neck) to mature state. RbfA interacts with 3`-end of 16S rRNA on mRNA exit channel and stabilizes the conformation of the region between h28, h44/h45 linker and 3`-end. Methods: Pure S.aureus RbfA was obtained by homologous expression in E.coli BL21 strain followed by Ni-NTA and gel filtration. The 30S subunits were obtained by dissociation of the S.aureus 70S ribosomes in a sucrose gradient (0-30%). We performed 30S subunit and RbfA complex reconstitution, sample and grid preparation. Data was collected on Talos Arctica, Falcon 2 detector (FEI Company/Thermo Fisher). Results: The 30S-RbfA complex density map with average resolution ~ 3.5 Å (FSC=0.143) was obtained. In comparison with the free subunit map (EMD 23052) we observed an extra density on the neck region near the decoding center region. Conclusion: Obtained data is correlated with recent structural results of the homologous E.coli RbfA. We consider that S.aureus RbfA binds to the 30S subunit at the same region. The next step of our structural research is building the model of S.aureus 30S-RbfA complex.

Background: Antibiotic resistance is a growing worldwide problem. One of the major resistant bacterial pathogens is Staphylococcus aureus, which became a burden of healthcare systems around the world. To overcome the issue, more drug discovery studies are needed. One of the main antibiotic targets is a ribosome – the central hub of protein synthesis. Structural data of the ribosome and its features are a crucial milestone for the effective development of new drugs, especially using structure-based drug design approaches. Apart from many small structural features, ribosome possesses rRNA modifications that play a role in the fine-tuning of protein synthesis. Detailed species-specific structural data of the S. aureus ribosome is also a useful model for understanding the resistance mechanisms. This information could help with the design of new antibiotics and the upgrading of old ones. The data on S. aureus ribosomal RNA modifications and corresponding modification enzymes are very limited. Our aim was to improve the current models of the S. aureus ribosome by determining its structure with functional ligands at a much higher resolution - thereby creating a foundation for structure-based drug design experiments and research of new drug targets. Methods: The S. aureus ribosome complex consists of three components: ribosome, fMet-tRNAfMet, mRNA and 70S ribosome. The complex from purified components was formed in vitro and applied to cryo-EM grids. Data was collected at Titan Krios with Gatan K2 detector (IGBMC, France). The data was processed and modeled in Relion 2.1, Chimera, Coot, and Phenix. Results: We determined the cryo-EM reconstruction at 3.2 Å resolution of the S. aureus ribosome with P-site tRNA, messenger RNA. Based on the experimental map and existing bioinformatic data, we at the first time identified and assigned 10 modifications of S. aureus rRNA. We analyzed the positions of rRNA modifications and their possible functions. Conclusion: In this study, we describe our structure of S. aureus ribosome with functional ligands. The present model is the highest resolution and most precise that is available at the moment. We propose a set of methyltransferases as targets for future drug discovery studies. The proposed methyltransferases and corresponding modifications may play an important role in protein synthesis and its regulation.

Staphylococcus aureus: hibernation-promoting factor (SaHPF) is a 22.2 kDa stationary-phase protein that binds to the ribosome and turns it to the inactive form favoring survival under stress. Sequence analysis has shown that this protein is combination of two homolog proteins obtained in Escherichia coli—ribosome hibernation promoting factor (HPF) (11,000 Da) and ribosome modulation factor RMF (6500 Da). Binding site of E. coli HPF on the ribosome have been shown by X-ray study of Thermus thermophilus ribosome complex. Hence, recent studies reported that the interface is markedly different between 100S from S. aureus and E. coli. Cryo-electron microscopy structure of 100S S. aureus ribosomes reveal that the SaHPF-NTD binds to the 30S subunit as observed for shorter variants of HPF in other species and the C-terminal domain (CTD) protrudes out of each ribosome in order to mediate dimerization. SaHPF-NTD binds to the small subunit similarly to its homologs EcHPF, EcYfiA, and a plastid-specific YfiA. Furthermore, upon binding to the small subunit, the SaHPF-NTD occludes several antibiotic binding sites at the A site (hygromycin B, tetracycline), P site (edeine) and E site (pactamycin, kasugamycin). In order to elucidate the structure, dynamics and function of SaHPF-NTD from S. aureus, here we report the backbone and side chain resonance assignments for SaHPF-NTD. Analysis of the backbone chemical shifts by TALOS+ suggests that SaHPF-NTD contains two α-helices and four β-strands (β1-α1-β2-β3-β4-α2 topology). Investigating the long-term survival of S. aureus and other bacteria under antibiotic pressure could lead to advances in antibiotherapy.

The ribosome, the largest RNA-containing macromolecular machinery in cells, requires metal ions not only to maintain its three-dimensional fold but also to perform protein synthesis. Despite the vast biochemical data regarding the importance of metal ions for efficient protein synthesis and the increasing number of ribosome structures solved by X-ray crystallography or cryo-electron microscopy, the assignment of metal ions within the ribosome remains elusive due to methodological limitations. Here we present extensive experimental data on the potassium composition and environment in two structures of functional ribosome complexes obtained by measurement of the potassium anomalous signal at the K-edge, derived from long-wavelength X-ray diffraction data. We elucidate the role of potassium ions in protein synthesis at the three-dimensional level, most notably, in the environment of the ribosome functional decoding and peptidyl transferase centers. Our data expand the fundamental knowledge of the mechanism of ribosome function and structural integrity., Metal ions play essential roles in myriads of biological processes, from catalytic co-factors to supporting protein and nucleic acid structures. Here the authors use long-wavelength X-ray diffraction to locate hundreds of potassium ions taking part in the formation of rRNA tertiary structure, mediating rRNA–protein interactions and supporting ribosomal protein structures and function.

Background: In bacteria, diminishing of protein synthesis is often accompanied with the formation of ribosomal dimers (or disomes). This process might be particularly important for pathogenic bacteria whose successful survival is a key factor for successful infection. Ribosome hibernation is driven by the binding of small stress-induced protein(s) to 70S ribosomes forming stable 100S ribosomal dimers. In contrast with E. coli where ribosome dimerization occurs in the presence of two proteins: hibernation promoting factor (HPF, 95 aa residues) and ribosome modulation factor (RMF, 55 aa residues) in Staphylococcus aureus only one protein (long version of HPF) is responsible for the formation of hibernating ribosome dimers, which in turn play a role in survival of this pathogen under unfavorable conditions. Methods: By cryo-electron microscopy we obtained a high-resolution structure of the 100S ribosome dimer and by NMR spectroscopy and X-ray crystallography solved a NTD and CTD of SaHPF protein structures. Results: Our recent cryo-EM studies demonstrated that integrity of 100S disomes is maintained primarily by interactions between C-terminal domains (CTD) of SaHPF with each other. N-terminal domain (NTD) of SaHPF binds to the 30S subunit at the P-site and A-site and may inhibit protein synthesis as observed for shorter variants of HPF in other species. By NMR spectroscopy we have determined the solution structure of SaHPF-NTD and analyzed its binding with S. aureus 70S ribosome. Conclusion: Based on NMR and crystal structures of SaHFP-CTD we predicted the key amino acids residues stabilizing dimer interface and made several single amino acid substitutions which allows us to abolish the ribosome hibernation. Obtained information about crucial for dimerization residues in long HPF may be used as a potential target for combating S. aureus.

Elongation factor P (EF-P) is a three domain protein that binds to the ribosome between P and E sites.The EF-P involved in a specialized translation of stalling amino acid motifs such as (PPP or APP). Proteins with stalling motifs are involved in various cell processes, including stress resistance and virulence of bacteria. EF-P stabilizes the P-tRNA and increases the entropy of stalled ribosome complex to compensate for rigid nature of proline residue, thus providing adequate protein synthesis rate. Detailed structural mechanisms of this effect are still poorly understood. It was shown that most of bacteria needs a special post-translational modification in a conservative region of the loop in the domain I of the EF-P located near the CCA-end of P-tRNA and the peptidyl transferase center. In present paper by EPR spectroscopy we investigated a spinlabeled EF-P from Staphylococcus aureus—a pathogenic bacteria which causes various human diseases. Addition of MTSL ((S-(1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)methyl methanesulfonothioate)) label covalently bound to 32Cys in the highly conservative part of EF-P loop in the domain I of the EF-P allows us to analyze protein dynamic by EPR spectroscopy of the high mobility region which was not observed in NMR spectra due to fast proton exchange leading to the absence of the corresponding amide NMR resonances. We suppose that our result could be extended in future for the analysis of EF-P—ribosome complex formation process by advanced EPR techniques.

For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version).ABSTRACT The article examines the role of coal and its contribution to the profitability and volumes of transportation of JSC Russian Railways. Tariffs for transportation of coal by rail and transport (rail) component in the final price of this type of fuel were analyzed. It is shown how the railway tariffs and the transportation distance affect the competitiveness of the Russian coal industry. Keywords: railway, transportation, tariffs, coal, price, transport component, rates of rolling stock operators, competitiveness. REFERENCES 1.Transportation research board special report 318.Modernizing freight rail regulation, Washington, D.C., 2015, 279 p. 2.Khusainov, F. I. Unregulated railway tariffs: the Russian experience of 1850-1880s [Nereguliruemye zheleznodorozhnye tarify: rossijskij opyt 1850-1880-h godov].Bulletin of transport information, 2009, Iss.8, pp.15-22. 3.Khusainov, F. I. Reform of the railway industry in Russia: the problems of unfinished liberalization.Monograph [Reforma zheleznodorozhnoj otrasli v Rossii: problemy nezavershjonnoj liberalizacii. Monografija].Moscow, Nauka publ., 2015, 272 p. 4.Khusainov, F. I. Russia’s accession to the WTO and rail transport [Vstuplenie Rossii v VTO i zheleznodorozhnyj transport].Bulletin of transport information, 2012, Iss.9, pp.9-15. 5.Kudiyarov, S. Let’s give coal to the country! [Dajosh’ strane uglja!].Expert, 2013, October 14. 6.Markova, V., Churashev, V. The Way of Coal [Put’ uglja].Expert-Siberia, 2013, 03 June. 7.Empty promises G20 subsidies to oil, gas and coal production.London, 2015, 103 p. 8.Khusainov, F. I. Towards a new price list: what about coal? [Navstrechu novomu prejskurantu: kak byt’ s ugljom?].RZD-Partner, July 13, 2016.[Electronic resource]: http://www.rzd-partner.ru/zhd-transport/news/ navstrechu-novomu-preiskurantu - kak-byt-s-ugliom/?sphrase_id=632.Last accessed 14.09.2016.

A procedure is proposed for the design of a "structural geotechnogenic massif," which permits the selection of a cost-effective technology for reinforcing soil with soil-cement elements at the design phase, thus assuring the required level of settling.

International audience; In bacteria, ribosomal hibernation shuts down translation as a response to stress, through reversible binding of stress-induced proteins to ribosomes. This process typically involves the formation of 100S ribosome dimers. Here, we present the structures of hibernating ribosomes from human pathogen Staphylococcus aureus containing a long variant of the hibernation-promoting factor (SaHPF) that we solved using cryo-electron microscopy. Our reconstructions reveal that the N-terminal domain (NTD) of SaHPF binds to the 30S subunit as observed for shorter variants of HPF in other species. The C-terminal domain (CTD) of SaHPF protrudes out of each ribosome in order to mediate dimerization. Using NMR, we characterized the interactions at the CTD-dimer interface. Secondary interactions are provided by helix 26 of the 16S ribosomal RNA We also show that ribosomes in the 100S particle adopt both rotated and unrotated conformations. Overall, our work illustrates a specific mode of ribosome dimerization by long HPF, a finding that may help improve the selectivity of antimicrobials.

© 2016, Pleiades Publishing, Inc.Staphylococcus aureus is a major opportunistic and versatile pathogen. Because the bacteria rapidly evolve multi-resistances towards antibiotics, there is an urgent need to find novel targets and alternative strategies to cure bacterial infections. Here, we provide a brief overview on the knowledge acquired on S. aureus ribosomes, which is one of the major antibiotic targets. We will show that subtle differences exist between the translation at the initiation step of Gram-negative and Gram-positive bacteria although their ribosomes display a remarkable degree of resemblance. In addition, we will illustrate using specific examples the diversity of mechanisms controlling translation initiation in S. aureus that contribute to shape the expression of the virulence factors in a temporal and dynamic manner.

Comparative structural studies of ribosomes from various organisms keep offering exciting insights on how species-specific or environment-related structural features of ribosomes may impact translation specificity and its regulation. Although the importance of such features may be less obvious within more closely related organisms, their existence could account for vital yet species-specific mechanisms of translation regulation that would involve stalling, cell survival and antibiotic resistance. Here, we present the first full 70S ribosome structure from Staphylococcus aureus, a Gram-positive pathogenic bacterium, solved by cryo-electron microscopy. Comparative analysis with other known bacterial ribosomes pinpoints several unique features specific to S. aureus around a conserved core, at both the protein and the RNA levels. Our work provides the structural basis for the many studies aiming at understanding translation regulation in S. aureus and for designing drugs against this often multi-resistant pathogen.