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ClpL is essential for induction of thermotolerance and is potentially part of the HrcA regulon in Lactobacillus gasseri
Author(s) -
Suokko Aki,
Poutanen Marjo,
Savijoki Kirsi,
Kalkkinen Nisse,
Varmanen Pekka
Publication year - 2008
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.200700925
Subject(s) - lactobacillus gasseri , biology , heat shock protein , heat shock , regulon , gene , probiotic , microbiology and biotechnology , groel , groes , mutant , bacteria , escherichia coli , genetics
Stress‐inducible proteins are likely to contribute to the survival and activity of probiotic bacteria during industrial processes and in the gastrointestinal tract. The recently published genome sequence of probiotic Lactobacillus gasseri ATCC 33323 suggests the presence of ClpC, ClpE, ClpL, and ClpX from the Clp ATPase family of stress proteins. The heat‐shock response of L. gasseri was studied using 2‐D DIGE. A total of 20 protein spots showing significant ( p <0.05) increase in abundance after 30 min heat‐shock were identified, including DnaK, GroEL, ClpC, ClpE, and ClpL. To study the physiological role of ClpL, one of the most highly induced proteins during heat‐shock, its corresponding gene was inactivated. The Δ clpL mutant strain had growth characteristics that were indistinguishable from wild‐type under several stress conditions. However, in the absence of functional ClpL, L. gasseri exhibited drastically reduced survival at a lethal temperature and was unable to induce thermotolerance. Genome sequences indicate that the expression of clp genes in several Lactobacillus species is regulated by HrcA, instead of CtsR, the conserved clp gene regulator of low G+C Gram‐positive bacteria. Electrophoretic mobility shift assays using L. gasseri HrcA protein and clpL upstream fragments revealed, for the first time, a direct interaction between HrcA and the promoter of a clp gene from a Lactobacillus .