Characterization of Campylobacter jejuni RacRS reveals roles in the heat shock response, motility, and maintenance of cell length homogeneity.
نویسندگان
چکیده
Campylobacter jejuni commensally colonizes the cecum of birds. The RacR (reduced ability to colonize) response regulator was previously shown to be important in avian colonization. To explore the means by which RacR and its cognate sensor kinase RacS may modulate C. jejuni physiology and colonization, ΔracR and ΔracS mutations were constructed in the invasive, virulent strain 81-176, and extensive phenotypic analyses were undertaken. Both the ΔracR and ΔracS mutants exhibited a ~100-fold defect in chick colonization despite no (ΔracS) or minimal (ΔracR) growth defects at 42 °C, the avian body temperature. Each mutant was defective for colony formation at 44°C and in the presence of 0.8% NaCl, both of which are stresses associated with the heat shock response. Promoter-reporter and real-time quantitative PCR (RT-qPCR) analyses revealed that RacR activates racRS and represses dnaJ. Although disregulation of several other heat shock genes was not observed at 38°C, the ΔracR and ΔracS mutants exhibited diminished upregulation of these genes upon a rapid temperature upshift. Furthermore, the ΔracR and ΔracS mutants displayed increased length heterogeneity during exponential growth, with a high proportion of filamented bacteria. Filamented bacteria had reduced swimming speed and were defective for invasion of Caco-2 epithelial cells. Soft-agar studies also revealed that the loss of racR or racS resulted in whole-population motility defects in viscous medium. These findings reveal new roles for RacRS in C. jejuni physiology, each of which is likely important during colonization of the avian host.
منابع مشابه
Characterization of Campylobacter jejuni RacRS reveals a role in the heat shock response , motility , and maintenance of cell length population homogeneity
متن کامل
Diverse roles for HspR in Campylobacter jejuni revealed by the proteome, transcriptome and phenotypic characterization of an hspR mutant.
Campylobacter jejuni is a leading cause of bacterial gastroenteritis in the developed world. The role of a homologue of the negative transcriptional regulatory protein HspR, which in other organisms participates in the control of the heat-shock response, was investigated. Following inactivation of hspR in C. jejuni, members of the HspR regulon were identified by DNA microarray transcript profil...
متن کاملInvestigation of Virulence-Associated genes and Cytolethal Distending Toxin Production in Campylobacter spp. isolated from broilers
The aim of this study was to investigate the prevalence of virulence and Cytolethal Distending Toxin (CDT) genes in the Campylobacter isolates from intestinal contents and gall bladders of broilers and, to evalute their cytotoxic effects on HeLa cell cultures. These genes play important roles in bacterial adherence to intestinal mucosa, flagella-mediated motility, invasive capability and the ab...
متن کاملHeat shock- and alkaline pH-induced proteins of Campylobacter jejuni: characterization and immunological properties.
The protein response to physiological stress was characterized in Campylobacter jejuni 81176 after exposure to heat and pH shock and following periods of recovery. Immunoreactivities of major stress-related proteins were determined with anti-Campylobacter immune rabbit serum and intestinal lavage fluid. Distinct proteins with molecular masses ranging from 10 to 120 kDa were induced and/or relea...
متن کاملUse of a Rabbit Soft Tissue Chamber Model to Investigate Campylobacter Jejuni–Host Interactions
Despite the prevalence of Campylobacter jejuni as an important food borne pathogen, the microbial factors governing its infection process are poorly characterized. In this study, we developed a novel rabbit soft tissue chamber model to investigate C. jejuni interactions with its host. The in vivo transcriptome profile of C. jejuni was monitored as a function of time post-infection by competitiv...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Journal of bacteriology
دوره 194 9 شماره
صفحات -
تاریخ انتشار 2012