sigmaB-dependent protein induction in Listeria monocytogenes during vancomycin stress.
Listeria monocytogenes is a food-borne pathogen that can survive under a wide range of environmental and energy stress conditions. The general stress response controlled by sigma(B) largely contributes to stress resistance in L. monocytogenes. Moreover, the bacterial cell wall is the first defense against cellular stress and as such is the target of numerous antibiotics. We therefore hypothesize that sigma(B) contributes to monitoring the integrity of cell walls. We evaluated sigma(B) activity in wild type and DeltasigB mutant L. monocytogenes containing reporter fusions (sigma(B)-dependent opuCA promoter and a lacZ reporter gene) during the early exponential growth phase by measuring the specific activity of beta-galactosidase after vancomycin (2 microg mL(-1) final concentration) stress. sigma(B) activity is significantly induced only in the wild-type strain by addition of vancomycin. In addition, we identified sigma(B)-dependent vancomycin-inducible proteins using LC-ESI-MS/MS analysis. Two independent proteomic analyses confirmed the minimum twofold upregulation of 18 vancomycin-inducible sigma(B)-dependent stress response proteins in the wild-type strain compared with the DeltasigB mutant. The functions of these proteins are associated with cell wall biogenesis, intracellular transport, general stress response, cell metabolism and virulence. These results suggest that the sigma(B) protein may contribute to the monitoring of cell wall integrity.
Shin
Ji-Hyun
JH
Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Korea. sjih@hotmail.com
Kim
Jungmin
J
Kim
Sung-Min
SM
Kim
Shukho
S
Lee
Je-Chul
JC
Ahn
Jung-Mo
JM
Cho
Je-Yoel
JY
D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D006801:Humans; D007763:Lac Operon; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000502:physiology*; D027701:Organic Cation Transport Proteins / Q000235:genetics; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological; D015854:Up-Regulation; D014640:Vancomycin / Q000633:toxicity*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
D001426:Bacterial Proteins; D027701:Organic Cation Transport Proteins; C079011:SigB protein, Bacteria; D012808:Sigma Factor; C492021:opuC protein, Listeria monocytogenes; D014640:Vancomycin; D001616:beta-Galactosidase