Motor rotation is essential for the formation of the periplasmic flagellar ribbon, cellular morphology, and Borrelia burgdorferi persistence within Ixodes scapularis tick and murine hosts.

Borrelia burgdorferi must migrate within and between its arthropod and mammalian hosts in order to complete its natural enzootic cycle. During tick feeding, the spirochete transmits from the tick to the host dermis, eventually colonizing and persisting within multiple, distant tissues. This dissemination modality suggests that flagellar motor rotation and, by extension, motility are crucial for infection.

The cyclic-di-GMP signaling pathway in the Lyme disease spirochete, Borrelia burgdorferi.

In nature, the Lyme disease spirochete Borrelia burgdorferi cycles between the unrelated environments of the Ixodes tick vector and mammalian host. In order to survive transmission between hosts, B. burgdorferi must be able to not only detect changes in its environment, but also rapidly and appropriately respond to these changes.

Motility is crucial for the infectious life cycle of Borrelia burgdorferi.

The Lyme disease spirochete, Borrelia burgdorferi, exists in a zoonotic cycle involving an arthropod tick and mammalian host. Dissemination of the organism within and between these hosts depends upon the spirochete's ability to traverse through complex tissues. Additionally, the spirochete outruns the host immune cells while migrating through the dermis, suggesting the importance of B.

Analysis of the HD-GYP domain cyclic dimeric GMP phosphodiesterase reveals a role in motility and the enzootic life cycle of Borrelia burgdorferi.

HD-GYP domain cyclic dimeric GMP (c-di-GMP) phosphodiesterases are implicated in motility and virulence in bacteria. Borrelia burgdorferi possesses a single set of c-di-GMP-metabolizing enzymes, including a putative HD-GYP domain protein, BB0374. Recently, we characterized the EAL domain phosphodiesterase PdeA.

CheY3 of Borrelia burgdorferi is the key response regulator essential for chemotaxis and forms a long-lived phosphorylated intermediate.

Spirochetes have a unique cell structure: These bacteria have internal periplasmic flagella subterminally attached at each cell end. How spirochetes coordinate the rotation of the periplasmic flagella for chemotaxis is poorly understood. In other bacteria, modulation of flagellar rotation is essential for chemotaxis, and phosphorylation-dephosphorylation of the response regulator CheY plays a key role in regulating this rotary motion.

A novel gene inactivation system reveals altered periplasmic flagellar orientation in a Borrelia burgdorferi fliL mutant.

Motility and chemotaxis are essential components of pathogenesis for many infectious bacteria, including Borrelia burgdorferi, the causative agent of Lyme disease. Motility and chemotaxis genes comprise 5 to 6% of the genome of B. burgdorferi, yet the functions of most of those genes remain uncharacterized, mainly due to the paucity of a nonpolar gene inactivation system.

Analysis of the Borrelia burgdorferi cyclic-di-GMP-binding protein PlzA reveals a role in motility and virulence.

The cyclic-dimeric-GMP (c-di-GMP)-binding protein PilZ has been implicated in bacterial motility and pathogenesis. Although BB0733 (PlzA), the only PilZ domain-containing protein in Borrelia burgdorferi, was reported to bind c-di-GMP, neither its role in motility or virulence nor it's affinity for c-di-GMP has been reported. We determined that PlzA specifically binds c-di-GMP with high affinity (dissociation constant [K(d)], 1.

Monitoring antimicrobial susceptibility of Neisseria gonorrhoeae isolated from Bangladesh during 1997-2006: emergence and pattern of drug-resistant isolates.

Gonorrhoea is one of the most common sexually transmitted infections (STIs) in developing countries, and the emergence of resistance to antimicrobial agents in Neisseria gonorrhoeae is a major obstacle in the control of gonorrhoea. Periodical monitoring of antimicrobial susceptibility of N. gonorrhoeae is essential for the early detection of emergence of drug resistance.

Analysis of a Borrelia burgdorferi phosphodiesterase demonstrates a role for cyclic-di-guanosine monophosphate in motility and virulence.

The genome of Borrelia burgdorferi encodes a set of genes putatively involved in cyclic-dimeric guanosine monophosphate (cyclic-di-GMP) metabolism. Although BB0419 was shown to be a diguanylate cyclase, the extent to which bb0419 or any of the putative cyclic-di-GMP metabolizing genes impact B. burgdorferi motility and pathogenesis has not yet been reported.

The PhoB regulatory system modulates biofilm formation and stress response in El Tor biotype Vibrio cholerae.

The PhoBR regulatory system is required for the induction of multiple genes under conditions of phosphate limitation. Here, we examine the role of PhoB in biofilm formation and environmental stress response in Vibrio cholerae of the El Tor biotype. Deletion of phoB or hapR enhanced biofilm formation in a phosphate-limited medium.

Modulation of Vibrio mimicus hemolysin through limited proteolysis by an endogenous metalloprotease.

Vibrio mimicus is a causative agent of human gastroenteritis and food poisoning, and this species produces an enterotoxic hemolysin (V. mimicus hemolysin) as a virulence determinant. Vibrio mimicus hemolysin is secreted as an 80 kDa precursor, which is later converted to the 66 kDa mature toxin through removal of an N-terminal propeptide via cleavage of the Arg151-Ser152 bond.

Cyclic AMP post-transcriptionally regulates the biosynthesis of a major bacterial autoinducer to modulate the cell density required to activate quorum sensing.

In Vibrio cholerae, expression of the quorum sensing regulator HapR is induced by the accumulation of a major autoinducer synthesized by the activity of CqsA. Here we show that the cAMP-cAMP receptor protein complex regulates cqsA expression at the post-transcriptional level. This conclusion is supported by the analysis of cqsA-lacZ fusions, the ectopic expression of cqsA in Deltacrp mutants and by Northern blot analysis showing that cqsA mRNA is unstable in Deltacrp and Deltacya (adenylate cyclase) mutants.

Role of the histone-like nucleoid structuring protein in the regulation of rpoS and RpoS-dependent genes in Vibrio cholerae.

Production of the Zn-metalloprotease hemagglutinin (HA)/protease by Vibrio cholerae has been reported to enhance enterotoxicity in rabbit ileal loops and the reactogenicity of live cholera vaccine candidates. Expression of HA/protease requires the alternate sigma factor sigma(S) (RpoS), encoded by rpoS. The histone-like nucleoid structuring protein (H-NS) has been shown to repress rpoS expression in Escherichia coli.