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https://www.readbyqxmd.com/read/28323618/contact-dependent-killing-by-caulobacter-crescentus-via-cell-surface-associated-glycine-zipper-proteins
#1
Leonor Garcia-Bayona, Monica S Guo, Michael T Laub
Most bacteria are in fierce competition with other species for limited nutrients. Some bacteria can kill nearby cells by secreting bacteriocins, a diverse group of proteinaceous antimicrobials. However, bacteriocins are typically freely diffusible, and so of little value to planktonic cells in aqueous environments. Here, we identify an atypical two-protein bacteriocin in the α-proteobacterium Caulobacter crescentus that is retained on the surface of producer cells where it mediates cell contact-dependent killing...
March 21, 2017: ELife
https://www.readbyqxmd.com/read/28288813/a-genomically-modified-escherichia-coli-strain-carrying-an-orthogonal-e-coli-histidyl-trna-synthetase%C3%A2-trna-his-pair
#2
Markus Englert, Oscar Vargas-Rodriguez, Noah M Reynolds, Yane-Shih Wang, Dieter Söll, Takuya Umehara
BACKGROUND: Development of new aminoacyl-tRNA synthetase (aaRS)•tRNA pairs is central for incorporation of novel non-canonical amino acids (ncAAs) into proteins via genetic code expansion (GCE). The Escherichia coli and Caulobacter crescentus histidyl-tRNA synthetases (HisRS) evolved divergent mechanisms of tRNA(His) recognition that prevent their cross-reactivity. Although the E. coli HisRS•tRNA(His) pair is a good candidate for GCE, its use in C. crescentus is limited by the lack of established genetic selection methods and by the low transformation efficiency of C...
March 10, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28274196/asymmetric-cellular-memory-in-bacteria-exposed-to-antibiotics
#3
Roland Mathis, Martin Ackermann
BACKGROUND: The ability to form a cellular memory and use it for cellular decision-making could help bacteria to cope with recurrent stress conditions. We analyzed whether bacteria would form a cellular memory specifically if past events are predictive of future conditions. We worked with the asymmetrically dividing bacterium Caulobacter crescentus where past events are expected to only be informative for one of the two cells emerging from division, the sessile cell that remains in the same microenvironment and does not migrate...
March 9, 2017: BMC Evolutionary Biology
https://www.readbyqxmd.com/read/28256791/conformational-behaviour-of-mannuronic-acid-based-azasugars
#4
Erwin van Rijssel, Antonius Janssen, Alexandra Males, Gideon Davies, Gijsbert van der Marel, Hermen S Overkleeft, Jeroen Codée
A set of mannuronic acid based iminosugars, comprising the C-5-carboxylic acid, -methyl ester and -amide analogues of 1-deoxymannorjirimicin (DMJ), was synthesized and their pH dependent conformational behavior studied. Under acidic conditions the methyl ester and the carboxylic acid took up an "inverted" 1C4 chair conformation as opposed to the "normal" 4C1 chair at basic pH. This conformational change is explained by the stereoelectronic effects of the ring substituents and it parallels the behavior of the mannuronic acid ester oxocarbenium ion...
March 3, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28246363/a-localized-complex-of-two-protein-oligomers-controls-the-orientation-of-cell-polarity
#5
Adam M Perez, Thomas H Mann, Keren Lasker, Daniel G Ahrens, Michael R Eckart, Lucy Shapiro
Signaling hubs at bacterial cell poles establish cell polarity in the absence of membrane-bound compartments. In the asymmetrically dividing bacterium Caulobacter crescentus, cell polarity stems from the cell cycle-regulated localization and turnover of signaling protein complexes in these hubs, and yet the mechanisms that establish the identity of the two cell poles have not been established. Here, we recapitulate the tripartite assembly of a cell fate signaling complex that forms during the G1-S transition...
February 28, 2017: MBio
https://www.readbyqxmd.com/read/28167520/a-new-essential-cell-division-protein-in-caulobacter-crescentus
#6
Aurora Osorio, Laura Camarena, Miguel Angel Cevallos, Sebastian Poggio
Bacterial cell division is a complex process that relies on a multiprotein complex composed of a core of widely conserved and generally essential proteins and on accessory proteins that vary in number and identity in different bacteria. The assembly of this complex and in particular, the initiation of constriction is a regulated process that has come under intensive study. In this work, we characterize the function of DipI, a protein conserved in alpha and beta proteobacteria that is essential in Caulobacter crescentus Our results show that DipI is a periplasmic protein that is recruited late to the division site and that is required for the initiation of constriction...
February 6, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28138140/hit-the-right-spots-cell-cycle-control-by-phosphorylated-guanosines-in-alphaproteobacteria
#7
REVIEW
Régis Hallez, Marie Delaby, Stefano Sanselicio, Patrick H Viollier
The class Alphaproteobacteria includes Gram-negative free-living, symbiotic and obligate intracellular bacteria, as well as important plant, animal and human pathogens. Recent work has established the key antagonistic roles that phosphorylated guanosines, cyclic-di-GMP (c-di-GMP) and the alarmones guanosine tetraphosphate and guanosine pentaphosphate (collectively referred to as (p)ppGpp), have in the regulation of the cell cycle in these bacteria. In this Review, we discuss the insights that have been gained into the regulation of the initiation of DNA replication and cytokinesis by these second messengers, with a particular focus on the cell cycle of Caulobacter crescentus...
January 31, 2017: Nature Reviews. Microbiology
https://www.readbyqxmd.com/read/28104475/effects-of-cry1ab-bt-maize-straw-return-on-bacterial-community-of-earthworm-eisenia-fetida
#8
Yinghua Shu, Yanyan Zhang, Huilan Zeng, Yahui Zhang, Jianwu Wang
The eco-toxicological effects of Bacillus thuringiensis (Bt) maize on earthworm life-history traits were widely studied and the results were controversial, while their effects on earthworm bacterial community have been rarely studied. Here, effects of two hybrids of Bt maize [5422Bt1 (event Bt11) and 5422CBCL (MON810)] straw return on Eisenia fetida bacterial community were investigated by the terminal restriction fragment length polymorphism (T-RFLP) and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) combing with DNA sequencing, compared to near-isogenic non-Bt maize (5422)...
January 7, 2017: Chemosphere
https://www.readbyqxmd.com/read/28035693/identification-of-a-u-zn-cu-responsive-global-regulatory-two-component-system-in-caulobacter-crescentus
#9
Dan M Park, K Wesley Overton, Megan J Liou, Yongqin Jiao
Despite the well-known toxicity of uranium (U) to bacteria, little is known about how cells sense and respond to U. The recent finding of a U-specific stress response in Caulobacter crescentus has provided a foundation for studying the mechanisms of U- perception in bacteria. To gain insight into this process, we used a forward genetic screen to identify the regulatory components governing expression of the urcA promoter (PurcA ) that is strongly induced by U. This approach unearthed a previously uncharacterized two-component system, named UzcRS, which is responsible for U-dependent activation of PurcA ...
December 30, 2016: Molecular Microbiology
https://www.readbyqxmd.com/read/28031282/tonb-dependent-heme-hemoglobin-utilization-by-caulobacter-crescentus-huta
#10
Heloise Balhesteros, Yan Shipelskiy, Noah J Long, Aritri Majumdar, Benjamin B Katz, Naara M Santos, Laura Leaden, Salete M Newton, Marilis V Marques, Phillip E Klebba
Siderophore nutrition tests with Caulobacter crescentus strain NA1000 revealed that it utilized a variety of ferric hydroxamate siderophores, including asperchromes, ferrichromes, ferrichrome A, malonichrome, and ferric aerobactin, as well as hemin and hemoglobin. C. crescentus did not transport ferrioxamine B or ferric catecholates. Because it did not use ferric enterobactin, the catecholate aposiderophore was an effective agent for iron deprivation. We determined the kinetics and thermodynamics of [(59)Fe]apoferrichrome and (59)Fe-citrate binding and transport by NA1000...
March 15, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28012062/a-synthetic-hybrid-promoter-for-xylose-regulated-control-of-gene-expression-in-saccharomyces-yeasts
#11
Ronald E Hector, Jeffrey A Mertens
Metabolism of non-glucose carbon sources is often highly regulated at the transcriptional and post-translational levels. This level of regulation is lacking in Saccharomyces cerevisiae strains engineered to metabolize xylose. To better control transcription in S. cerevisiae, the xylose-dependent, DNA-binding repressor (XylR) from Caulobacter crescentus was used to block transcription from synthetic promoters based on the constitutive Ashbya gossypii TEF promoter. The new hybrid promoters were repressed in the absence of xylose and showed up to a 25-fold increase in the presence of xylose...
December 23, 2016: Molecular Biotechnology
https://www.readbyqxmd.com/read/28011580/replication-fork-passage-drives-asymmetric-dynamics-of-a-critical-nucleoid-associated-protein-in-caulobacter
#12
Rodrigo Arias-Cartin, Genevieve S Dobihal, Manuel Campos, Ivan V Surovtsev, Bradley Parry, Christine Jacobs-Wagner
In bacteria, chromosome dynamics and gene expression are modulated by nucleoid-associated proteins (NAPs), but little is known about how NAP activity is coupled to cell cycle progression. Using genomic techniques, quantitative cell imaging, and mathematical modeling, our study in Caulobacter crescentus identifies a novel NAP (GapR) whose activity over the cell cycle is shaped by DNA replication. GapR activity is critical for cellular function, as loss of GapR causes severe, pleiotropic defects in growth, cell division, DNA replication, and chromosome segregation...
February 1, 2017: EMBO Journal
https://www.readbyqxmd.com/read/28008852/modularity-and-determinants-of-a-bi-polarization-control-system-from-free-living-and-obligate-intracellular-bacteria
#13
Matthieu Bergé, Sébastien Campagne, Johann Mignolet, Seamus Holden, Laurence Théraulaz, Suliana Manley, Frédéric H-T Allain, Patrick H Viollier
Although free-living and obligate intracellular bacteria are both polarized it is unclear whether the underlying polarization mechanisms and effector proteins are conserved. Here we dissect at the cytological, functional and structural level a conserved polarization module from the free living α-proteobacterium Caulobacter crescentus and an orthologous system from an obligate intracellular (rickettsial) pathogen. The NMR solution structure of the zinc-finger (ZnR) domain from the bifunctional and bipolar ZitP pilus assembly/motility regulator revealed conserved interaction determinants for PopZ, a bipolar matrix protein that anchors the ParB centromere-binding protein and other regulatory factors at the poles...
December 23, 2016: ELife
https://www.readbyqxmd.com/read/28008851/functional-dichotomy-and-distinct-nanoscale-assemblies-of-a-cell-cycle-controlled-bipolar-zinc-finger-regulator
#14
Johann Mignolet, Seamus Holden, Matthieu Bergé, Gaël Panis, Ezgi Eroglu, Laurence Théraulaz, Suliana Manley, Patrick H Viollier
Protein polarization underlies differentiation in metazoans and in bacteria. How symmetric polarization can instate functional asymmetry remains elusive. Here, we show by super-resolution photo-activated localization microscopy and edgetic mutations that the bitopic zinc-finger protein ZitP implements specialized developmental functions - pilus biogenesis and multifactorial swarming motility - while shaping distinct nanoscale (bi)polar architectures in the asymmetric model bacterium Caulobacter crescentus. Polar assemblage and accumulation of ZitP and its effector protein CpaM are orchestrated in time and space by conserved components of the cell cycle circuitry that coordinate polar morphogenesis with cell cycle progression, and also act on the master cell cycle regulator CtrA...
December 23, 2016: ELife
https://www.readbyqxmd.com/read/27998932/toxin-inhibition-in-c-crescentus-vapbc1-is-mediated-by-a-flexible-pseudo-palindromic-protein-motif-and-modulated-by-dna-binding
#15
Kirstine L Bendtsen, Kehan Xu, Majbritt Luckmann, Kristoffer S Winther, Shiraz A Shah, Christian N S Pedersen, Ditlev E Brodersen
Expression of bacterial type II toxin-antitoxin (TA) systems is regulated at the transcriptional level through direct binding of the antitoxin to pseudo-palindromic sequences on operator DNA. In this context, the toxin functions as a co-repressor by stimulating DNA binding through direct interaction with the antitoxin. Here, we determine crystal structures of the complete 90 kDa heterooctameric VapBC1 complex from Caulobacter crescentus CB15 both in isolation and bound to its cognate DNA operator sequence at 1...
December 19, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27997543/cell-cycle-constraints-and-environmental-control-of-local-dna-hypomethylation-in-%C3%AE-proteobacteria
#16
Silvia Ardissone, Peter Redder, Giancarlo Russo, Antonio Frandi, Coralie Fumeaux, Andrea Patrignani, Ralph Schlapbach, Laurent Falquet, Patrick H Viollier
Heritable DNA methylation imprints are ubiquitous and underlie genetic variability from bacteria to humans. In microbial genomes, DNA methylation has been implicated in gene transcription, DNA replication and repair, nucleoid segregation, transposition and virulence of pathogenic strains. Despite the importance of local (hypo)methylation at specific loci, how and when these patterns are established during the cell cycle remains poorly characterized. Taking advantage of the small genomes and the synchronizability of α-proteobacteria, we discovered that conserved determinants of the cell cycle transcriptional circuitry establish specific hypomethylation patterns in the cell cycle model system Caulobacter crescentus...
December 2016: PLoS Genetics
https://www.readbyqxmd.com/read/27941972/a-kinase-phosphatase-switch-transduces-environmental-information-into-a-bacterial-cell-cycle-circuit
#17
Kristina Heinrich, Patrick Sobetzko, Kristina Jonas
The bacterial cell cycle has been extensively studied under standard growth conditions. How it is modulated in response to environmental changes remains poorly understood. Here, we demonstrate that the freshwater bacterium Caulobacter crescentus blocks cell division and grows to filamentous cells in response to stress conditions affecting the cell membrane. Our data suggest that stress switches the membrane-bound cell cycle kinase CckA to its phosphatase mode, leading to the rapid dephosphorylation, inactivation and proteolysis of the master cell cycle regulator CtrA...
December 2016: PLoS Genetics
https://www.readbyqxmd.com/read/27905486/biochemical-and-structural-analysis-of-a-novel-esterase-from-caulobacter-crescentus-related-to-penicillin-binding-protein-pbp
#18
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
https://www.readbyqxmd.com/read/27893963/regulated-proteolysis-in-bacteria-caulobacter
#19
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
https://www.readbyqxmd.com/read/27893179/ctra-controls-cell-division-and-outer-membrane-composition-of-the-pathogen-brucella-abortus
#20
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
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