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Cold shock proteins and low-temperature response of Streptococcus thermophilus CNRZ302.

ABSTRACT: Low-temperature adaptation and cryoprotection were studied in the thermophilic lactic acid bacterium Streptococcus thermophilus CNRZ302. S. thermophilus actively adapts to freezing during a pretreatment at 20 degrees C, resulting in an approximately 1, 000-fold increased survival after four freeze-thaw cycles compared to mid-exponential-phase cells grown at an optimal temperature of 42 degrees C. No adaptation is observed when cells are exposed to a temperature (10 degrees C) below the minimal growth temperature of the strain (just below 15 degrees C). By two-dimensional gel electrophoresis several 7-kDa cold-induced proteins were identified, which are the major induced proteins after a shift to 20 degrees C. These cold shock proteins were maximally expressed at 20 degrees C, while the induction level was low after cold shock to 10 degrees C. To confirm the presence of csp genes in S. thermophilus, a PCR strategy was used which yielded products of different sizes. Sequence analysis revealed csp-like sequences that were up to 95% identical to those of csp genes of S. thermophilus ST1-1, Streptococcus dysgalactiae, Streptococcus pyogenes, and Lactococcus lactis. Northern blot analysis revealed a seven- to ninefold induction of csp mRNA after a temperature shift to 20 degrees C, showing that this thermophilic bacterium indeed contains at least one cold-inducible csp gene and that its regulation takes place at the transcriptional level.

SUBMITTER: Wouters JA

PROVIDER: S-EPMC91590 | biostudies-literature | 1999 Oct

REPOSITORIES: biostudies-literature

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Cold shock proteins and low-temperature response of Streptococcus thermophilus CNRZ302.

Wouters J A JA Rombouts F M FM de Vos W M WM Kuipers O P OP Abee T T

Applied and environmental microbiology 19991001 10

Low-temperature adaptation and cryoprotection were studied in the thermophilic lactic acid bacterium Streptococcus thermophilus CNRZ302. S. thermophilus actively adapts to freezing during a pretreatment at 20 degrees C, resulting in an approximately 1, 000-fold increased survival after four freeze-thaw cycles compared to mid-exponential-phase cells grown at an optimal temperature of 42 degrees C. No adaptation is observed when cells are exposed to a temperature (10 degrees C) below the minimal g ...[more]

PMID: 10508072

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Project description:Vibrio parahaemolyticus causes serious seafood-borne gastroenteritis and death in humans. Raw seafood is often subjected to post-harvest processing and low-temperature storage. To date, very little information is available regarding the biological functions of cold shock proteins (CSPs) in the low-temperature survival of the bacterium. In this study, we determined the complete genome sequence of V. parahaemolyticus CHN25 (serotype: O5:KUT). The two main CSP-encoding genes (VpacspA and VpacspD) were deleted from the bacterial genome, and comparative transcriptomic analysis between the mutant and wild-type strains was performed to dissect the possible molecular mechanisms that underlie low-temperature adaptation by V. parahaemolyticus.The 5,443,401-bp?V. parahaemolyticus CHN25 genome (45.2% G?+?C) consisted of two circular chromosomes and three plasmids with 4,724 predicted protein-encoding genes. One dual-gene and two single-gene deletion mutants were generated for VpacspA and VpacspD by homologous recombination. The growth of the ?VpacspA mutant was strongly inhibited at 10 °C, whereas the VpacspD gene deletion strongly stimulated bacterial growth at this low temperature compared with the wild-type strain. The complementary phenotypes were observed in the reverse mutants (?VpacspA-com, and ?VpacspD-com). The transcriptome data revealed that 12.4% of the expressed genes in V. parahaemolyticus CHN25 were significantly altered in the ?VpacspA mutant when it was grown at 10 °C. These included genes that were involved in amino acid degradation, secretion systems, sulphur metabolism and glycerophospholipid metabolism along with ATP-binding cassette transporters. However, a low temperature elicited significant expression changes for 10.0% of the genes in the ?VpacspD mutant, including those involved in the phosphotransferase system and in the metabolism of nitrogen and amino acids. The major metabolic pathways that were altered by the dual-gene deletion mutant (?VpacspAD) radically differed from those that were altered by single-gene mutants. Comparison of the transcriptome profiles further revealed numerous differentially expressed genes that were shared among the three mutants and regulators that were specifically, coordinately or antagonistically modulated by VpaCspA and VpaCspD. Our data also revealed several possible molecular coping strategies for low-temperature adaptation by the bacterium.This study is the first to describe the complete genome sequence of V. parahaemolyticus (serotype: O5:KUT). The gene deletions, complementary insertions, and comparative transcriptomics demonstrate that VpaCspA is a primary CSP in the bacterium, while VpaCspD functions as a growth inhibitor at 10 °C. These results have improved our understanding of the genetic basis for low-temperature survival by the most common seafood-borne pathogen worldwide.

Dataset Information

Cold shock proteins and low-temperature response of Streptococcus thermophilus CNRZ302.

Publications

Cold shock proteins and low-temperature response of Streptococcus thermophilus CNRZ302.

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