a protein thermometer controls temperature-dependent transcription of flagellar motility genes in listeria monocytogenes一种蛋白质温度计控制与温度有关的单核细胞增多性李斯特氏菌鞭毛运动基因的转录.pdfVIP

A Protein Thermometer Controls Temperature- Dependent Transcription of Flagellar Motility Genes in Listeria monocytogenes Heather D. Kamp, Darren E. Higgins* Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America Abstract Facultative bacterial pathogens must adapt to multiple stimuli to persist in the environment or establish infection within a host. Temperature is often utilized as a signal to control expression of virulence genes necessary for infection or genes required for persistence in the environment. However, very little is known about the molecular mechanisms that allow bacteria to adapt and respond to temperature fluctuations. Listeria monocytogenes (Lm) is a food-borne, facultative intracellular pathogen that uses flagellar motility to survive in the extracellular environment and to enhance initial invasion of host cells during infection. Upon entering the host, Lm represses transcription of flagellar motility genes in response to mammalian physiological temperature (37uC) with a concomitant temperature-dependent up-regulation of virulence genes. We previously determined that down-regulation of flagellar motility is required for virulence and is governed by the reciprocal activities of the MogR transcriptional repressor and the bifunctional flagellar anti-repressor/glycosyltransferase, GmaR. In this study, we determined that GmaR is also a protein thermometer that controls temperature-dependent transcription of flagellar motility genes. Two-hybrid and gel mobility shift analyses indicated that the interaction between MogR and GmaR is temperature sensitive. Using circular dichroism and limited proteolysis, we determined that GmaR undergoes a temperature-dependent conformational change as tempe