The cell division protein FzlA performs a conserved function in diverse alphaproteobacteria.

In almost all bacteria, the tubulin-like GTPase FtsZ polymerizes to form a "Z-ring" that marks the site of division. FtsZ recruits other proteins, collectively known as the divisome, that together remodel and constrict the envelope. Constriction is driven by peptidoglycan (PG) cell wall synthesis by the glycosyltransferase FtsW and the transpeptidase FtsI (FtsWI), but these enzymes require activation to function.

OpgH is an essential regulator of morphology.

Bacterial growth and division rely on intricate regulation of morphogenetic complexes to remodel the cell envelope without compromising envelope integrity. Significant progress has been made in recent years towards understanding the regulation of cell wall metabolic enzymes. However, other cell envelope components play a role in morphogenesis as well.

GTPase activity regulates FtsZ ring positioning in .

Bacterial cell division is crucial for replication and requires careful coordination via proteins collectively called the divisome. The tubulin-like GTPase FtsZ is the master regulator of this process and serves to recruit downstream divisome proteins and regulate their activities. Upon assembling at mid-cell, FtsZ exhibits treadmilling motion driven by GTP binding and hydrolysis.

House of CarDs: Functional insights into the transcriptional regulator CdnL.

Regulation of bacterial transcription is a complex and multi-faceted phenomenon that is critical for growth and adaptation. Proteins in the CarD_CdnL_TRCF family are widespread, often essential, regulators of transcription of genes required for growth and metabolic homeostasis. Research in the last decade has described the mechanistic and structural bases of CarD-CdnL-mediated regulation of transcription initiation.

Regulation of the transcription factor CdnL promotes adaptation to nutrient stress in .

In response to nutrient deprivation, bacteria activate a conserved stress response pathway called the stringent response (SR). During SR activation in , SpoT synthesizes the secondary messengers guanosine 5'-diphosphate 3'-diphosphate and guanosine 5'-triphosphate 3'-diphosphate (collectively known as (p)ppGpp), which affect transcription by binding RNA polymerase (RNAP) to down-regulate anabolic genes. (p)ppGpp also impacts the expression of anabolic genes by controlling the levels and activities of their transcriptional regulators.

Regulation of the transcription factor CdnL promotes adaptation to nutrient stress in .

In response to nutrient deprivation, bacteria activate a conserved stress response pathway called the stringent response (SR). During SR activation in , SpoT synthesizes the secondary messengers (p)ppGpp, which affect transcription by binding RNA polymerase to downregulate anabolic genes. (p)ppGpp also impacts expression of anabolic genes by controlling the levels and activities of their transcriptional regulators.

Integration of cell wall synthesis and chromosome segregation during cell division in Caulobacter.

To divide, bacteria must synthesize their peptidoglycan (PG) cell wall, a protective meshwork that maintains cell shape. FtsZ, a tubulin homolog, dynamically assembles into a midcell band, recruiting division proteins, including the PG synthases FtsW and FtsI. FtsWI are activated to synthesize PG and drive constriction at the appropriate time and place.

OpgH is an essential regulator of morphology.

Bacterial growth and division rely on intricate regulation of morphogenetic complexes to remodel the cell envelope without compromising envelope integrity. Significant progress has been made in recent years towards understanding the regulation of cell wall metabolic enzymes. However, other cell envelope components play a role in morphogenesis as well.

Quantitative analysis of morphogenesis and growth dynamics in an obligate intracellular bacterium.

Obligate intracellular bacteria of the order Rickettsiales include important human pathogens. However, our understanding of the biology of species is limited by challenges imposed by their obligate intracellular lifestyle. To overcome this roadblock, we developed methods to assess cell wall composition, growth, and morphology of , a human pathogen in the spotted fever group of the genus.

Synchronized Swarmers and Sticky Stalks: Caulobacter crescentus as a Model for Bacterial Cell Biology.

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.

EstG is a novel esterase required for cell envelope integrity in Caulobacter.

Proper regulation of the bacterial cell envelope is critical for cell survival. Identification and characterization of enzymes that maintain cell envelope homeostasis is crucial, as they can be targets for effective antibiotics. In this study, we have identified a novel enzyme, called EstG, whose activity protects cells from a variety of lethal assaults in the ⍺-proteobacterium Caulobacter crescentus.

FtsZ dynamics in bacterial division: What, how, and why?

Bacterial cell division is orchestrated by the divisome, a protein complex centered on the tubulin homolog FtsZ. FtsZ polymerizes into a dynamic ring that defines the division site, recruits downstream proteins, and directs peptidoglycan synthesis to drive constriction. Recent studies have documented treadmilling of FtsZ polymer clusters both in cells and in vitro.

Uncovering Unappreciated Activities and Niche Functions of Bacterial Cell Wall Enzymes.

A peptidoglycan (PG) cell wall is an essential component of nearly all bacteria, providing protection against turgor pressure. Metabolism of this PG meshwork must be spatially and temporally regulated in order to support cell growth and division. Despite being an active area of research for decades, we have only recently identified the primary PG synthesis complexes that function during cell elongation (RodA-PBP2) and cell division (FtsW-FtsI), and we are still uncovering the importance of the other seemingly redundant cell wall enzymes.

Bacterial cell division at a glance.

Bacterial cell division is initiated by the midcell assembly of polymers of the tubulin-like GTPase FtsZ. The FtsZ ring (Z-ring) is a discontinuous structure made of dynamic patches of FtsZ that undergo treadmilling motion. Roughly a dozen additional essential proteins are recruited to the division site by the dynamic Z-ring scaffold and subsequently activate cell wall synthesis to drive cell envelope constriction during division.

The conserved transcriptional regulator CdnL is required for metabolic homeostasis and morphogenesis in Caulobacter.

Bacterial growth and division require regulated synthesis of the macromolecules used to expand and replicate components of the cell. Transcription of housekeeping genes required for metabolic homeostasis and cell proliferation is guided by the sigma factor σ70. The conserved CarD-like transcriptional regulator, CdnL, associates with promoter regions where σ70 localizes and stabilizes the open promoter complex.

FtsA Regulates Z-Ring Morphology and Cell Wall Metabolism in an FtsZ C-Terminal Linker-Dependent Manner in Caulobacter crescentus.

Bacterial cell division requires the assembly of a multiprotein division machinery, or divisome, that remodels the cell envelope to cause constriction. The cytoskeletal protein FtsZ forms a ringlike scaffold for the divisome at the incipient division site. FtsZ has three major regions: a conserved GTPase domain that polymerizes into protofilaments on binding GTP, a C-terminal conserved peptide (CTC) required for binding membrane-anchoring proteins, and a C-terminal linker (CTL) region of varied length and low sequence conservation.

An Essential Regulator of Bacterial Division Links FtsZ to Cell Wall Synthase Activation.

Bacterial growth and division require insertion of new peptidoglycan (PG) into the existing cell wall by PG synthase enzymes. Emerging evidence suggests that many PG synthases require activation to function; however, it is unclear how activation of division-specific PG synthases occurs. The FtsZ cytoskeleton has been implicated as a regulator of PG synthesis during division, but the mechanisms through which it acts are unknown.

Agrobacterium tumefaciens divisome proteins regulate the transition from polar growth to cell division.

The mechanisms that restrict peptidoglycan biosynthesis to the pole during elongation and re-direct peptidoglycan biosynthesis to mid-cell during cell division in polar-growing Alphaproteobacteria are largely unknown. Here, we explore the role of early division proteins of Agrobacterium tumefaciens including three FtsZ homologs, FtsA and FtsW in the transition from polar growth to mid-cell growth and ultimately cell division. Although two of the three FtsZ homologs localize to mid-cell, exhibit GTPase activity and form co-polymers, only one, FtsZ , is required for cell division.

Species- and C-terminal linker-dependent variations in the dynamic behavior of FtsZ on membranes in vitro.

Bacterial cell division requires the assembly of FtsZ protofilaments into a dynamic structure called the 'Z-ring'. The Z-ring recruits the division machinery and directs local cell wall remodeling for constriction. The organization and dynamics of protofilaments within the Z-ring coordinate local cell wall synthesis during cell constriction, but their regulation is largely unknown.

FzlA, an essential regulator of FtsZ filament curvature, controls constriction rate during Caulobacter division.

During bacterial division, polymers of the tubulin-like GTPase FtsZ assemble at midcell to form the cytokinetic Z-ring, which coordinates peptidoglycan (PG) remodeling and envelope constriction. Curvature of FtsZ filaments promotes membrane deformation in vitro, but its role in division in vivo remains undefined. Inside cells, FtsZ directs PG insertion at the division plane, though it is unclear how FtsZ structure and dynamics are mechanistically coupled to PG metabolism.

The intrinsically disordered C-terminal linker of FtsZ regulates protofilament dynamics and superstructure .

The bacterial tubulin FtsZ polymerizes to form a discontinuous ring that drives bacterial cell division by directing local cell wall synthesis. FtsZ comprises a polymerizing GTPase domain, an intrinsically disordered C-terminal linker (CTL), and a C-terminal conserved peptide (CTC). FtsZ protofilaments align circumferentially in the cell, with the CTC mediating attachment to membrane-associated division proteins.

FtsEX-mediated regulation of the final stages of cell division reveals morphogenetic plasticity in Caulobacter crescentus.

During its life cycle, Caulobacter crescentus undergoes a series of coordinated shape changes, including generation of a polar stalk and reshaping of the cell envelope to produce new daughter cells through the process of cytokinesis. The mechanisms by which these morphogenetic processes are coordinated in time and space remain largely unknown. Here we demonstrate that the conserved division complex FtsEX controls both the early and late stages of cytokinesis in C.

A conserved coiled-coil protein pair focuses the cytokinetic Z-ring in Caulobacter crescentus.

The cytoskeletal GTPase FtsZ assembles at midcell, recruits the division machinery and directs envelope invagination for bacterial cytokinesis. ZapA, a conserved FtsZ-binding protein, promotes Z-ring stability and efficient division through a mechanism that is not fully understood. Here, we investigated the function of ZapA in Caulobacter crescentus.

Cytoskeletal Proteins in Caulobacter crescentus: Spatial Orchestrators of Cell Cycle Progression, Development, and Cell Shape.

Caulobacter crescentus, an aquatic Gram-negative α-proteobacterium, is dimorphic, as a result of asymmetric cell divisions that give rise to a free-swimming swarmer daughter cell and a stationary stalked daughter. Cell polarity of vibrioid C. crescentus cells is marked by the presence of a stalk at one end in the stationary form and a polar flagellum in the motile form.