Journal of Bacteriology

The prevalent transcriptional repressor NrdR binds to highly conserved sequences in the promoter regions of prokaryotic operons encoding the essential enzyme ribonucleotide reductase. The NrdR-binding sites consist of two partially palindromic 16 bp sequences (NrdR boxes) separated by a 15-16 bp linker sequence. We have assessed the requirement of both boxes for binding, the propensity of different NrdRs to bind to heterologous binding sites, and that the linker sequence is only limited to...

Staphylococcus aureus is one of the most frequently co-isolated pathogens in polymicrobial infections, where interspecies interactions contribute to enhanced virulence, persistence, and antimicrobial tolerance. Nutrient availability plays a central role in these interactions as microorganisms compete for resources to sustain essential cellular processes. For instance, branched-chain amino acids (BCAAs) are critical for protein synthesis, and valine synthesis pathway precursors are essential for...

Cell division is the ancient pathway by which bacteria synthesize a septum of peptidoglycan, dividing the cell into two. Although all walled bacteria were previously thought to use FtsW-FtsI orthologs to synthesize septal peptidoglycan during division, we recently discovered that the major pathogen Clostridioides difficile is missing FtsW-FtsI and instead relies on the activity of the bifunctional Class A penicillin-binding protein (PBP) called PBP1 to synthesize septal peptidoglycan during...

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The nucleotide diadenosine tetraphosphate (Ap(4)A) accumulates during stress across organisms and cell types and is widely hypothesized to be an alarmone or second messenger. While gram-negative bacteria use ApaH-family hydrolases to degrade Ap(4)A and other dinucleoside tetraphosphates (Ap(4)Ns), gram-positive bacteria, including Staphylococcus aureus, use YqeK. Inactivation of Ap(4)A hydrolases and corresponding Ap(4)A accumulation cause diverse phenotypic effects in gram-negative and...

The type VI secretion system (T6SS) is a nanomachine utilized by Gram-negative bacteria to secrete toxic effectors. The T6SS is employed against both prokaryotic and eukaryotic targets, allowing for competitive advantage and virulence of the attackers in a wide variety of environments. Recent work has revealed the great diversity of T6SS systems. Beyond the canonical, conserved architectural genes of the T6SS, diverse T6SS-associated genes (TAGs) are employed to optimize T6SS activity,...

Penetration of the peptidoglycan (PG) layer by the nascent flagellar rod is a critical step in basal body assembly and has long been attributed to the acetylglucosaminidase activity of the flagellar rod cap protein FlgJ. Previous work in Salmonella enterica suggested that occasional preexisting openings in the PG layer allow some flagella to assemble in the absence of the FlgJ enzymatic activity. More recently, studies in Bacillus subtilis demonstrated that membrane mobility of nascent flagellar...

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Prevotella species are an extremely common and abundant bacteria detected within the low microbial biomass of the lungs and are a core component of the oral microbiome. Clinical studies have drawn associations between Prevotella abundance and lung homeostasis, indicating potential relationships between Prevotella and lung inflammation, infection defense, and lung function. Across several studies in critically ill patients, the depletion of Prevotella and other obligate anaerobes is linked to...

Biofilm dispersion is a regulated process that enables bacteria to escape as free-living cells. This response coincides with matrix degradation, reduced cyclic di-GMP levels, heightened antibiotic susceptibility, and restored flagellar motility. While dispersed cells have been reported to be motile, the mechanisms enabling motility upon induction of dispersion remain unclear. Here, we explored the regulatory mechanism of how Pseudomonas aeruginosa biofilm cells switch their motility phenotype to...

Toxin-antitoxin (TA) systems are genetic modules widely distributed across bacterial chromosomes and mobile genetic elements. Initially described as plasmid addiction systems that ensure vertical inheritance through post-segregational killing, they are now recognized as versatile regulators of bacterial adaptability. In Helicobacter pylori, a gastric pathogen infecting nearly half of the global population, multiple TA systems have been experimentally validated, including type I RNA-RNA modules...

Orientia tsutsugamushi (Ot) is a cytoplasmic, gram-negative, obligate intracellular bacterium that causes the human disease scrub typhus. It has a highly repetitive genome, whereby approximately 50% is composed of multiple copies of a proliferated integrative and conjugative element, the Rickettsial amplified Genetic Element (RAGE). Previous RNA sequencing analysis revealed a high level of antisense transcription in Ot, particularly from RAGE-encoded genes, with 18% of all genes having a...

Type IV pili (T4P) drive social (S) motility in Myxococcus xanthus through cycles of extension and retraction powered by the ATPases PilB and PilT. Although the canonical retraction ATPase PilT is essential for force generation, M. xanthus encodes four PilT-like paralogs whose contributions to motility remain unclear. Here, we identify MXAN_1995 as the long-sought PilU protein that serves as a second T4P retraction motor. A frameshift mutation or deletion of pilU abolishes S-motility while...

The flagellar motor of Pseudomonas aeruginosa operates in a near-unbiased manner, extending the classical paradigm established by Escherichia coli. Rather than altering rotational bias, P. aeruginosa achieves chemotaxis by symmetrically modulating the dwell times of the two rotational states. This strategy is associated with a mechanically adaptive dual-stator architecture (MotAB and MotCD) and is further modulated by c-di-GMP signaling and auxiliary proteins such as FliL and MotY. At the...