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Bum Han Ryu, Tri Duc Ngo, Wanki Yoo, Sojeong Lee, Boo-Young Kim, Euijoo Lee, Kyeong Kyu Kim, T Doohun Kim
Considering that the prevalence of antibiotic-resistant pathogenic bacteria is largely increasing, a thorough understanding of penicillin-binding proteins (PBPs) is of great importance and crucial significance because this enzyme family is a main target of β-lactam-based antibiotics. In this work, combining biochemical and structural analysis, we present new findings that provide novel insights into PBPs. Here, a novel PBP homologue (CcEstA) from Caulobacter crescentus CB15 was characterized using native-PAGE, mass spectrometry, gel filtration, CD spectroscopy, fluorescence, reaction kinetics, and enzyme assays toward various substrates including nitrocefin...
December 1, 2016: Scientific Reports
Kamal Kishore Joshi, Peter Chien
Protein degradation is essential for all living things. Bacteria use energy-dependent proteases to control protein destruction in a highly specific manner. Recognition of substrates is determined by the inherent specificity of the proteases and through adaptor proteins that alter the spectrum of substrates. In the α-proteobacterium Caulobacter crescentus, regulated protein degradation is required for stress responses, developmental transitions, and cell cycle progression. In this review, we describe recent progress in our understanding of the regulated and stress-responsive protein degradation pathways in Caulobacter...
November 23, 2016: Annual Review of Genetics
Nayla Francis, Katy Poncin, Antonella Fioravanti, Victoria Vassen, Kevin Willemart, Thi Anh Phuong Ong, Luca Rappez, Jean-Jacques Letesson, Emanuele G Biondi, Xavier De Bolle
Brucella abortus is a pathogen infecting cattle, able to survive, traffic and proliferate inside host cells. It belongs to the Alphaproteobacteria, a phylogenetic group comprising bacteria with free living, symbiotic and pathogenic lifestyles. An essential regulator of cell cycle progression named CtrA was described in the model bacterium Caulobacter crescentus. This regulator is conserved in many alphaproteobacteria, but the evolution of its regulon remains elusive. Here we identified promoters that are CtrA targets using ChIP-seq and we found that CtrA binds to promoters of genes involved in cell cycle progression, in addition to numerous genes encoding outer membrane components involved in export of membrane proteins and synthesis of lipopolysaccharide...
November 28, 2016: Molecular Microbiology
Alex Nyarko, Hazel Barton, Ali Dhinojwala
The adhesion of two materials in the presence of water is greatly impeded by a boundary layer of water between the adhesive and the adherend, resulting in adhesive failure of most synthetic adhesives; however, life evolved first in water and there are many aquatic organisms that have to overcome this impediment to underwater adhesion. For example, multicellular aquatic organisms like the mussel, sandcastle worm and the caddisfly larva employ well-studied adhesive mechanisms for sticking in the presence of water...
November 16, 2016: Soft Matter
Jared M Schrader, Gene-Wei Li, W Seth Childers, Adam M Perez, Jonathan S Weissman, Lucy Shapiro, Harley H McAdams
Progression of the Caulobacter cell cycle requires temporal and spatial control of gene expression, culminating in an asymmetric cell division yielding distinct daughter cells. To explore the contribution of translational control, RNA-seq and ribosome profiling were used to assay global transcription and translation levels of individual genes at six times over the cell cycle. Translational efficiency (TE) was used as a metric for the relative rate of protein production from each mRNA. TE profiles with similar cell cycle patterns were found across multiple clusters of genes, including those in operons or in subsets of operons...
November 1, 2016: Proceedings of the National Academy of Sciences of the United States of America
Balaganesh Janakiraman, Johann Mignolet, Sharath Narayanan, Patrick H Viollier, Sunish Kumar Radhakrishnan
Cell fate determination in the asymmetric bacterium Caulobacter crescentus (Caulobacter) is triggered by the localization of the developmental regulator SpmX to the old (stalked) cell pole during the G1→S transition. Although SpmX is required to localize and activate the cell fate-determining kinase DivJ at the stalked pole in Caulobacter, in cousins such as Asticcacaulis, SpmX directs organelle (stalk) positioning and possibly other functions. We define the conserved σ(54)-dependent transcriptional activator TacA as a global regulator in Caulobacter whose activation by phosphorylation is indirectly down-regulated by SpmX...
October 17, 2016: Proceedings of the National Academy of Sciences of the United States of America
Joshua A Holmes, Shelby E Follett, Haibi Wang, Christopher P Meadows, Krisztina Varga, Grant R Bowman
Despite their relative simplicity, bacteria have complex anatomy at the subcellular level. At the cell poles of Caulobacter crescentus, a 177-amino acid (aa) protein called PopZ self-assembles into 3D polymeric superstructures. Remarkably, we find that this assemblage interacts directly with at least eight different proteins, which are involved in cell cycle regulation and chromosome segregation. The binding determinants within PopZ include 24 aa at the N terminus, a 32-aa region near the C-terminal homo-oligomeric assembly domain, and portions of an intervening linker region...
November 1, 2016: Proceedings of the National Academy of Sciences of the United States of America
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...
January 2017: 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...
November 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
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