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Current Opinion in Microbiology Apr 2021In the past decades, Caulobacter crescentus has been extensively studied, mostly regarding its dimorphic, asymmetric life cycle. Its distinct mode of reproduction and... (Review)
Review
In the past decades, Caulobacter crescentus has been extensively studied, mostly regarding its dimorphic, asymmetric life cycle. Its distinct mode of reproduction and the need to optimally adapt to ever-changing environmental conditions require tight coordination of gene regulation. Post-transcriptional regulation through non-coding RNAs and RNA-binding proteins constitutes an important layer of expression control in bacteria, but its principles and mechanisms in Caulobacter have only recently been explored. RNA-binding proteins including the RNA chaperone Hfq and ribonuclease RNase E contribute to the activity of regulatory RNAs. Riboswitches and RNA thermometers govern expression of downstream open reading frames, while the small regulatory RNAs CrfA, ChvR and GsrN instead control targets encoded in trans by direct base-pairing interactions.
Topics: Bacterial Proteins; Base Pairing; Caulobacter crescentus; Gene Expression Regulation, Bacterial; RNA, Bacterial; RNA, Messenger; RNA, Small Untranslated
PubMed: 33529919
DOI: 10.1016/j.mib.2021.01.002 -
Biochimica Et Biophysica Acta. Gene... Jul 2019Caulobacter crescentus is a free-living Alphaproteobacterium that thrives in oligotrophic environments. This review focuses on the regulatory network used by this... (Review)
Review
Caulobacter crescentus is a free-living Alphaproteobacterium that thrives in oligotrophic environments. This review focuses on the regulatory network used by this bacterium to control the levels of cell division proteins, their organization inside the cell and their activity as a function of the cell cycle. Strikingly, C. crescentus makes frequent use of master transcriptional regulators and epigenetic signals, most likely to synchronize cell division with other events of the cell cycle. In addition, cellular metabolism and DNA damage sensors emerge as central players regulating cell division in response to changing environmental conditions.
Topics: Bacterial Proteins; Caulobacter crescentus; Cell Division; DNA Damage; Gene Expression Regulation, Bacterial; Gene Regulatory Networks; Stress, Physiological
PubMed: 29715525
DOI: 10.1016/j.bbagrm.2018.04.005 -
Trends in Microbiology Aug 2017Bacterial cell shape is a genetically encoded and inherited feature that is optimized for efficient growth, survival, and propagation of bacteria. In addition, bacterial... (Review)
Review
Bacterial cell shape is a genetically encoded and inherited feature that is optimized for efficient growth, survival, and propagation of bacteria. In addition, bacterial cell morphology is adaptable to changes in environmental conditions. Work in recent years has demonstrated that individual features of cell shape, such as length or curvature, arise through the spatial regulation of cell wall synthesis by cytoskeletal proteins. However, the mechanisms by which these different morphogenetic factors are coordinated and how they may be globally regulated in response to cell cycle and environmental cues are only beginning to emerge. Here, we have summarized recent advances that have been made to understand morphology in the dimorphic Gram-negative bacterium Caulobacter crescentus.
Topics: Bacterial Proteins; Caulobacter crescentus; Cell Cycle; Cell Division; Cell Wall; Cytoskeletal Proteins; Cytoskeleton; Microbial Viability; Peptidoglycan; Stress, Physiological
PubMed: 28359631
DOI: 10.1016/j.tim.2017.03.006 -
FEMS Microbiology Reviews Jan 2012Caulobacter crescentus uses a multi-layered system of oscillating regulators to program different developmental fates into each daughter cell at division. This is... (Review)
Review
Caulobacter crescentus uses a multi-layered system of oscillating regulators to program different developmental fates into each daughter cell at division. This is achieved by superimposing gene expression, subcellular localization, phosphorylation, and regulated proteolysis to form a complex regulatory network that integrates chromosome replication, segregation, polar differentiation, and cytokinesis. In this review, we outline the current state of research in the field of Caulobacter development, emphasizing new findings that elaborate how the developmental program is modulated by factors such as the environment or the metabolic state of the cell.
Topics: Caulobacter crescentus; Cell Division; Gene Expression Regulation; Signal Transduction
PubMed: 22091823
DOI: 10.1111/j.1574-6976.2011.00309.x -
Annual Review of Genetics Nov 2016Protein degradation is essential for all living things. Bacteria use energy-dependent proteases to control protein destruction in a highly specific manner. Recognition... (Review)
Review
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. We discuss how organization of highly specific adaptors into functional hierarchies drives destruction of proteins during the bacterial cell cycle. Because all cells must balance the need for degradation of many true substrates with the toxic consequences of nonspecific protein destruction, principles found in one system likely generalize to others.
Topics: Bacterial Proteins; Caulobacter; Cell Cycle; Peptide Hydrolases; Proteolysis; Stress, Physiological
PubMed: 27893963
DOI: 10.1146/annurev-genet-120215-035235 -
PLoS Genetics Nov 2023The xenobiotic response element (XRE) family of transcription factors (TFs), which are commonly encoded by bacteria and bacteriophage, regulate diverse features of...
The xenobiotic response element (XRE) family of transcription factors (TFs), which are commonly encoded by bacteria and bacteriophage, regulate diverse features of bacterial cell physiology and impact phage infection dynamics. Through a pangenome analysis of Caulobacter species isolated from soil and aquatic ecosystems, we uncovered an apparent radiation of a paralogous XRE TF gene cluster, several of which have established functions in the regulation of holdfast adhesin development and biofilm formation in C. crescentus. We further discovered related XRE TFs throughout the class Alphaproteobacteria and its phages, including the φCbK Caulophage, suggesting that members of this cluster impact host-phage interactions. Here we show that a closely related group of XRE transcription factors encoded by both C. crescentus and φCbK can physically interact and function to control the transcription of a common gene set, influencing processes including holdfast development and the production of φCbK virions. The φCbK-encoded XRE paralog, tgrL, is highly expressed at the earliest stages of infection and can directly inhibit transcription of host genes including hfiA, a potent holdfast inhibitor, and gafYZ, an activator of prophage-like gene transfer agents (GTAs). XRE proteins encoded from the C. crescentus chromosome also directly repress gafYZ transcription, revealing a functionally redundant set of host regulators that may protect against spurious production of GTA particles and inadvertent cell lysis. Deleting the C. crescentus XRE transcription factors reduced φCbK burst size, while overexpressing these host genes or φCbK tgrL rescued this burst defect. We conclude that this XRE TF gene cluster, shared by C. crescentus and φCbK, plays an important role in adhesion regulation under phage-free conditions, and influences host-phage dynamics during infection.
Topics: Transcription Factors; Bacteriophages; Caulobacter; Ecosystem; Xenobiotics; Caulobacter crescentus; Adhesins, Bacterial; Response Elements
PubMed: 37972151
DOI: 10.1371/journal.pgen.1011048 -
Current Biology : CB Jul 2012
Topics: Caulobacter crescentus; Flagella; Gene Expression Regulation, Bacterial
PubMed: 22789993
DOI: 10.1016/j.cub.2012.05.036 -
Journal of Bacteriology Feb 2023First isolated and classified in the 1960s, Caulobacter crescentus has been instrumental in the study of bacterial cell biology and differentiation. C. crescentus is a... (Review)
Review
First isolated and classified in the 1960s, Caulobacter crescentus has been instrumental in the study of bacterial cell biology and differentiation. C. crescentus is a Gram-negative alphaproteobacterium that exhibits a dimorphic life cycle composed of two distinct cell types: a motile swarmer cell and a nonmotile, division-competent stalked cell. Progression through the cell cycle is accentuated by tightly controlled biogenesis of appendages, morphological transitions, and distinct localization of developmental regulators. These features as well as the ability to synchronize populations of cells and follow their progression make C. crescentus an ideal model for answering questions relevant to how development and differentiation are achieved at the single-cell level. This review will explore the discovery and development of C. crescentus as a model organism before diving into several key features and discoveries that have made it such a powerful organism to study. Finally, we will summarize a few of the ongoing areas of research that are leveraging knowledge gained over the last century with C. crescentus to highlight its continuing role at the forefront of cell and developmental biology.
Topics: Caulobacter crescentus; Cell Cycle; Cell Division; Bacterial Proteins
PubMed: 36715542
DOI: 10.1128/jb.00384-22 -
Journal of Bacteriology Oct 2023A suite of molecular sensory systems enables to control growth, development, and reproduction in response to levels of essential elements. The bacterial...
A suite of molecular sensory systems enables to control growth, development, and reproduction in response to levels of essential elements. The bacterial enhancer-binding protein (bEBP) NtrC and its cognate sensor histidine kinase, NtrB, are key regulators of nitrogen assimilation in many bacteria, but their roles in metabolism and development are not well defined. Notably, NtrC is an unconventional bEBP that lacks the σ-interacting loop commonly known as the GAFTGA motif. Here we show that deletion of slows cell growth in complex medium and that and are essential when ammonium is the sole nitrogen source due to their requirement for glutamine synthetase expression. Random transposition of a conserved IS3-family mobile genetic element frequently rescued the growth defect of mutant strains by restoring transcription of the operon, revealing a possible role for IS3 transposition in shaping the evolution of populations during nutrient limitation. We further identified dozens of direct NtrC-binding sites on the chromosome, with a large fraction located near genes involved in polysaccharide biosynthesis. The majority of binding sites align with those of the essential nucleoid-associated protein, GapR, or the cell cycle regulator, MucR1. NtrC is therefore predicted to directly impact the regulation of cell cycle and cell development. Indeed, loss of NtrC function led to elongated polar stalks and elevated synthesis of cell envelope polysaccharides. This study establishes regulatory connections between NtrC, nitrogen metabolism, polar morphogenesis, and envelope polysaccharide synthesis in . IMPORTANCE Bacteria balance cellular processes with the availability of nutrients in their environment. The NtrB-NtrC two-component signaling system is responsible for controlling nitrogen assimilation in many bacteria. We have characterized the effect of and deletion on growth and development and uncovered a role for spontaneous IS element transposition in the rescue of transcriptional and nutritional deficiencies caused by mutation. We further defined the regulon of NtrC, a bacterial enhancer-binding protein, and demonstrate that it shares specific binding sites with essential proteins involved in cell cycle regulation and chromosome organization. Our work provides a comprehensive view of transcriptional regulation mediated by a distinctive NtrC protein, establishing its connection to nitrogen assimilation and developmental processes in .
Topics: Base Sequence; Caulobacter; Nitrogen; Bacterial Proteins; DNA-Binding Proteins; Polysaccharides; Gene Expression Regulation, Bacterial; PII Nitrogen Regulatory Proteins
PubMed: 37791753
DOI: 10.1128/jb.00181-23 -
Current Opinion in Microbiology Dec 2013In rod shaped bacteria, numerous cellular components are targeted to the cell poles, and such localization is often important for optimal function. In particular,... (Review)
Review
In rod shaped bacteria, numerous cellular components are targeted to the cell poles, and such localization is often important for optimal function. In particular, recognition of poles is often linked to division site selection, chromosome segregation, chemotactic signaling, and motility. Recent advances in understanding polarity include identification of a Vibrio cholerae protein that mediates polar localization of a chromosome origin and chemotaxis clusters, as well as a downstream protein that contributes solely to localization of chemotaxis proteins. In Caulobacter crescentus, the molecular mechanisms by which polar determinants and effectors are localized, and the key roles for nucleotide-dependent switches, have been defined. Finally, roles for, and interactions between, factors that mediate environmentally determined polarity in Myxococcus xanthus have recently been characterized.
Topics: Caulobacter crescentus; Cell Polarity; Myxococcus xanthus; Vibrio cholerae
PubMed: 24029491
DOI: 10.1016/j.mib.2013.08.006