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Young-Ho Yoon, Clive S Barker, Paula V Bulieris, Hideyuki Matsunami, Fadel A Samatey
Across bacteria, the protein that makes the flagellar hook, FlgE, has a high variability in amino acid residue composition and sequence length. We hereby present the structure of two fragments of FlgE protein from Campylobacter jejuni and from Caulobacter crescentus, which were obtained by X-ray crystallography, and a high-resolution model of the hook from Caulobacter. By comparing these new structures of FlgE proteins, we show that bacterial hook can be divided in two distinct parts. The first part comprises domains that are found in all FlgE proteins and that will make the basic structure of the hook that is common to all flagellated bacteria...
October 19, 2016: Scientific Reports
Meng Yang, Jinshao Ye, Huaming Qin, Yan Long, Yi Li
Perfluorooctanoic acid (PFOA) has received an increasing attention in the agricultural and food industries due to its risk to human health. To facilitate the development of novel biomarkers of Escherichia coli against PFOA through multi-omics technologies, and to reveal the resistance mechanism of E. coli against PFOA at protein levels, the interactions among pollutant stress, protein expression and cell metabolism was investigated by using iTRAQ-based quantitative proteomic analysis. The results revealed that the 63 up-regulated proteins mainly involved in tricarboxylic acid cycle, glyoxylate and dicarboxylate metabolism and fatty acid biosynthesis, whereas, the 69 down-regulated proteins related to oxidative phosphorylation, pyruvate metabolism and the cell cycle-caulobacter pathway, were also associated with the increase of membrane permeability, excessive expenditure of ATP, disruption of fatty acid biosynthesis under PFOA stress...
October 11, 2016: Environmental Pollution
A Miglio, V Stefanetti, M T Antognoni, K Cappelli, S Capomaccio, M Coletti, F Passamonti
BACKGROUND: Bacterial contamination of whole blood (WB) units can result in transfusion-transmitted infection, but the extent of the risk has not been established and may be underestimated in veterinary medicine. OBJECTIVES: To detect, quantify, and identify bacterial microorganisms in 49 canine WB units during their shelf life. ANIMALS: Forty-nine healthy adult dogs. METHODS: Forty-nine WB units were included in the study...
October 13, 2016: Journal of Veterinary Internal Medicine
W Wurihan, W Wunier, H Li, L F Fan, M Morigen
The trans-translation pathway, mediated by the transfer messenger RNA (tmRNA; encoded by the ssrA gene) and the SmpB protein (tmRNA-binding protein expressed in Salmonella enterica), which is conserved in bacteria, is required for various cellular processes. A previous study has shown that trans-translation is required to ensure timely (non-delayed) dnaA transcription and consequent initiation of DNA replication in Caulobacter crescentus. In this study, we observed that initiation of chromosome replication was delayed in Escherichia coli lacking the smpB and/or ssrA genes (DssrA, DsmpB, or DsmpBDssrA mutants)...
August 29, 2016: Genetics and Molecular Research: GMR
Jing Liu, Laura I Francis, Kristina Jonas, Michael T Laub, Peter Chien
The Clp family of proteases is responsible for controlling both stress responses and normal growth. In Caulobacter crescentus, the ClpXP protease is essential and drives cell cycle progression through adaptor-mediated degradation. By contrast, the physiological role for the ClpAP protease is less well understood with only minor growth defects previously reported for ΔclpA cells. Here, we show that ClpAP plays an important role in controlling chromosome content and cell fitness during extended growth. Cells lacking ClpA accumulate aberrant numbers of chromosomes upon prolonged growth suggesting a defect in replication control...
September 26, 2016: Molecular Microbiology
K Wesley Overton, Dan M Park, Mimi C Yung, Alice C Dohnalkova, John Smit, Yongqin Jiao
Surface layers, or S-layers, are two-dimensional protein arrays that form the outermost layer of many bacteria and archaea. They serve several functions including physical protection of the cell from environmental threats. The high abundance of S-layer proteins necessitates a highly efficient export mechanism to transport S-layer protein from the cytoplasm to the cell exterior. Caulobacter crescentus is unique in that it has two homologous, seemingly redundant outer membrane proteins, RsaFa and RsaFb, that, together with other components, form a type I protein translocation pathway for S-layer export...
September 23, 2016: Applied and Environmental Microbiology
Badri N Dubey, Christian Lori, Shogo Ozaki, Geoffrey Fucile, Ivan Plaza-Menacho, Urs Jenal, Tilman Schirmer
Histidine kinases are key components of regulatory networks in bacteria. Although many of these enzymes are bifunctional, mediating both phosphorylation and dephosphorylation of downstream targets, the molecular details of this central regulatory switch are unclear. We showed recently that the universal second messenger cyclic di-guanosine monophosphate (c-di-GMP) drives Caulobacter crescentus cell cycle progression by forcing the cell cycle kinase CckA from its default kinase into phosphatase mode. We use a combination of structure determination, modeling, and functional analysis to demonstrate that c-di-GMP reciprocally regulates the two antagonistic CckA activities through noncovalent cross-linking of the catalytic domain with the dimerization histidine phosphotransfer (DHp) domain...
September 2016: Science Advances
Federica Penner, Silvia Brossa, Anna Maria Barbui, Alessandro Ducati, Rossana Cavallo, Francesco Zenga
BACKGROUND: Caulobacter spp. are Gram-negative bacteria that have rarely been found to be pathogenic in humans. CASE DESCRIPTION: This report describes the first case, to our knowledge, of meningitis in an adult patient caused by Caulobacter spp. A 75-year-old man was operated for a glioblastoma with no evident signs of primary infection in the wound site. Eight days after surgery, the patient developed signs and symptoms of meningitis. Caulobacter was then isolated on 3 separate occasions in the patient's cerebrospinal fluid...
September 17, 2016: World Neurosurgery
Dante P Ricci, Michael D Melfi, Keren Lasker, David L Dill, Harley H McAdams, Lucy Shapiro
Faithful cell cycle progression in the dimorphic bacterium Caulobacter crescentus requires spatiotemporal regulation of gene expression and cell pole differentiation. We discovered an essential DNA-associated protein, GapR, that is required for Caulobacter growth and asymmetric division. GapR interacts with adenine and thymine (AT)-rich chromosomal loci, associates with the promoter regions of cell cycle-regulated genes, and shares hundreds of recognition sites in common with known master regulators of cell cycle-dependent gene expression...
October 4, 2016: Proceedings of the National Academy of Sciences of the United States of America
Michael D Jones, Anson C K Chan, John F Nomellini, Michael E P Murphy, John Smit
Protein surface layers are self-assembling, paracrystalline lattices on the surface of many prokaryotes. Surface-layer proteins have not benefited from widespread structural analysis owing to their resistance to crystallization. Here, the successful expression of a truncated version of RsaA, the surface-layer protein from Caulobacter crescentus, from a Caulobacter protein-expression system is reported. The purification, crystallization and initial X-ray diffraction analysis of the truncated RsaA, the largest surface-layer protein studied to date and the first from a Gram-negative bacterium, are also reported...
September 2016: Acta Crystallographica. Section F, Structural Biology Communications
Clare L Kirkpatrick, Daniel Martins, Peter Redder, Antonio Frandi, Johann Mignolet, Julien Bortoli Chapalay, Marc Chambon, Gerardo Turcatti, Patrick H Viollier
Bacterial toxin-antitoxin systems (TASs) are thought to respond to various stresses, often inducing growth-arrested (persistent) sub-populations of cells whose housekeeping functions are inhibited. Many such TASs induce this effect through the translation-dependent RNA cleavage (RNase) activity of their toxins, which are held in check by their cognate antitoxins in the absence of stress. However, it is not always clear whether specific mRNA targets of orthologous RNase toxins are responsible for their phenotypic effect, which has made it difficult to accurately place the multitude of TASs within cellular and adaptive regulatory networks...
2016: Nature Microbiology
Emeline Lawarée, Sébastien Gillet, Gwennaëlle Louis, Françoise Tilquin, Sophie Le Blastier, Pierre Cambier, Jean-Yves Matroule
Stress response to fluctuating environments often implies a time-consuming reprogramming of gene expression. In bacteria, the so-called bet hedging strategy, which promotes phenotypic stochasticity within a cell population, is the only fast stress response described so far(1). Here, we show that Caulobacter crescentus asymmetrical cell division allows an immediate bimodal response to a toxic metals-rich environment by allocating specific defence strategies to morphologically and functionally distinct siblings...
2016: Nature Microbiology
Robert H Vass, Rilee D Zeinert, Peter Chien
Cell growth requires the removal of proteins that are unwanted or toxic. In bacteria, AAA+ proteases like the Clp family and Lon selectively destroy proteins defined by intrinsic specificity or adaptors. Caulobacter crescentus is a gram-negative bacterium that undergoes an obligate developmental transition every cell division cycle. Here we highlight recent work that reveals how a hierarchy of adaptors targets the degradation of key proteins at specific times during this cell cycle, integrating protein destruction with other cues...
August 17, 2016: Current Opinion in Microbiology
Keren Lasker, Thomas H Mann, Lucy Shapiro
Cellular functions in Bacteria, such as chromosome segregation and cytokinesis, result from cascades of molecular events operating largely as self-contained modules. Regulated timing of these cellular modules stems from global genetic circuits that allow precise temporal activation with respect to cell cycle progression and cell differentiation. Critically, many of these functions occur at defined locations within the cell, and therefore regulators of each module must communicate to remain coordinated in space...
October 2016: Current Opinion in Microbiology
Pushkar P Lele, Thibault Roland, Abhishek Shrivastava, Yihao Chen, Howard C Berg
Caulobacter crescentus, a monotrichous bacterium, swims by rotating a single right-handed helical filament. CW motor rotation thrusts the cell forward (1), a mode of motility known as the pusher mode; CCW motor rotation pulls the cell backward, a mode of motility referred to as the puller mode (2). The situation is opposite in E. coli, a peritrichous bacterium, where CCW rotation of multiple left-handed filaments drives the cell forward. The flagellar motor in E. coli generates more torque in the CCW direction than the CW direction in swimming cells (3,4)...
February 2016: Nature Physics
Mohammad Mubinur Rahman, Martina Andberg, Anu Koivula, Juha Rouvinen, Nina Hakulinen
L-Arabinonate dehydratase (EC and D-xylonate dehydratase (EC are two enzymes that are involved in a nonphosphorylative oxidation pathway of pentose sugars. L-Arabinonate dehydratase converts L-arabinonate into 2-dehydro-3-deoxy-L-arabinonate, and D-xylonate dehydratase catalyzes the dehydration of D-xylonate to 2-dehydro-3-deoxy-D-xylonate. L-Arabinonate and D-xylonate dehydratases belong to the IlvD/EDD family, together with 6-phosphogluconate dehydratases and dihydroxyacid dehydratases...
August 2016: Acta Crystallographica. Section F, Structural Biology Communications
Ivan Gonçalves de Castro Ferreira, Mirian Molnar Rodrigues, José Freire da Silva Neto, Ricardo Ruiz Mazzon, Marilis do Valle Marques
Iron is an essential nutrient that is poorly available to living organisms but can be harmful when in excess due to the production of reactive oxygen species. Bacteria and other organisms use iron storage proteins called ferritins to avoid iron toxicity and as a safe iron source in the cytosol. The alpha-proteobacterium Caulobacter crescentus has two putative ferritins, Bfr and Dps, and some other proteins belonging to the ferritin-like superfamily, among them the one encoded by CC_0557. In this work, we have analyzed the role and regulation of these three putative ferritin-like proteins...
October 2016: Biometals: An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine
Saumya Saurabh, Adam M Perez, Colin J Comerci, Lucy Shapiro, W E Moerner
The rapid development in fluorescence microscopy and imaging techniques has greatly benefited our understanding of the mechanisms governing cellular processes at the molecular level. In particular, super-resolution microscopy methods overcome the diffraction limit to observe nanoscale cellular structures with unprecedented detail, and single-molecule tracking provides precise dynamic information about the motions of labeled proteins and oligonucleotides. Enhanced photostability of fluorescent labels (i.e., maximum emitted photons before photobleaching) is a critical requirement for achieving the ultimate spatio-temporal resolution with either method...
August 24, 2016: Journal of the American Chemical Society
Satish Adhikari, Patrick D Curtis
Epigenetics is a change in gene expression that is heritable without a change in DNA sequence itself. This phenomenon is well studied in eukaryotes, particularly in humans for its role in cellular differentiation, X chromosome inactivation and diseases like cancer. However, comparatively little is known about epigenetic regulation in bacteria. Bacterial epigenetics is mainly present in the form of DNA methylation where DNA methyltransferases add methyl groups to nucleotides. This review focuses on two methyltransferases well characterized for their roles in gene regulation: Dam and CcrM...
September 2016: FEMS Microbiology Reviews
Yuanchao Zhan, Sijun Huang, Sonja Voget, Meinhard Simon, Feng Chen
Bacteria in the Roseobacter lineage have been studied extensively due to their significant biogeochemical roles in the marine ecosystem. However, our knowledge on bacteriophage which infects the Roseobacter clade is still very limited. Here, we report a new bacteriophage, phage DSS3Φ8, which infects marine roseobacter Ruegeria pomeroyi DSS-3. DSS3Φ8 is a lytic siphovirus. Genomic analysis showed that DSS3Φ8 is most closely related to a group of siphoviruses, CbK-like phages, which infect freshwater bacterium Caulobacter crescentus...
2016: Scientific Reports
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