Role of Cold Shock Proteins in Growth of Listeria monocytogenes under Cold and Osmotic Stress Conditions

Abstract

The gram-positive bacterium Listeria monocytogenes is a food-borne pathogen of both public health and food safety significance. It possesses three small, highly homologous protein members of the cold shock protein (Csp) family. We used gene expression analysis and a set of mutants with single, double, and triple deletions of the csp genes to evaluate the roles of CspA, CspB, and CspD in the cold and osmotic (NaCl) stress adaptation responses of L. monocytogenes. All three Csps are dispensable for growth at optimal temperature (37°C). These proteins are, however, required for efficient cold and osmotic stress tolerance of this bacterium. The hierarchies of their functional importance differ, depending on the environmental stress conditions: CspA>CspD>CspB in response to cold stress versus CspD>CspA/CspB in response to NaCl salt osmotic stress. The fact that Csps are promoting L. monocytogenes adaptation against both cold and NaCl stress has significant implications in view of practical food microbial control measures. The combined or sequential exposure of L. monocytogenes cells to these two stresses in food environments might inadvertently induce cross-protection responses.

Cold Shock Genes cspA and cspB from Caulobacter crescentus Are Posttranscriptionally Regulated and Important for Cold Adaptation

“…This family of proteins is widespread throughout bacteria, presenting a highly divergent number of paralogues in each organism. They respond not exclusively to temperature downshift but also to osmotic and oxidative stresses, stationary phase, carbon starvation, and antibiotic resistance, and some may even be constitutively expressed (6,9,10,39,42,54). Escherichia coli has nine csp paralogues, of which five are exclusively cold induced, one is constitutively expressed, and one is a replication inhibitor induced at stationary phase and under carbon starvation (26,54).…”

SpdR, a Response Regulator Required for Stationary-Phase Induction of Caulobacter crescentus cspD

“…The cold shock protein family includes small polypeptides (7 kDa) that are induced upon temperature downshift and stationary phase (15,24). Bacterial cells usually have multiple copies of csp genes, and different subsets of these have distinct patterns of expression, being induced by one or more of these stimuli: cold shock, stationary phase, high osmolarity, metal, H 2 O 2 , and antibiotics (8,15,16,26,42,52). The main proposed role of these proteins is as RNA chaperones maintaining the nucleic acids free from secondary structure at low temperatures, as described for E. coli CspA (24,26).…”

Ocorrência e diferenciação de espécies de Listeria spp. em salsichas tipo hot dog a granel e em amostras de carne moída bovina comercializadas no Distrito Federal

“…A ocorrência dessa bactéria em alimentos cárneos refrigerados foi observada em 20% das amostras de frango na Malásia (GOH et al, 2012) e em 26,4% em carcaças bovinas na China (ZHU et al, 2012). Esse microrganismo apresenta como característica a tolerância a baixas temperaturas, o que favorece muitas vezes altas prevalências (SCHMID et al, 2009; I Faculdade de Medicina, Universidade de Brasília (UnB), Brasília, DF, Brasil.…”