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Applied and Environmental Microbiology, April 2005, p. 2061-2069, Vol. 71, No. 4
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.4.2061-2069.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Characterization of a Mobile clpL Gene from Lactobacillus rhamnosus

Aki Suokko, Kirsi Savijoki, Erja Malinen, Airi Palva, and Pekka Varmanen*

Division of Microbiology and Epidemiology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland

Received 6 August 2004/ Accepted 15 November 2004

Two genes encoding ClpL ATPase proteins were identified in a probiotic Lactobacillus rhamnosus strain, E-97800. Sequence analyses revealed that the genes, designated clpL1 and clpL2, share 80% identity. The clpL2 gene showed the highest degree of identity (98.5%) to a clpL gene from Lactobacillus plantarum WCFSI, while it was not detected in three other L. rhamnosus strains studied. According to Northern analyses, the expression of clpL1 and the clpL2 were induced during heat shock by >20- and 3-fold, respectively. The functional promoter regions were determined by primer extension analyses, and the clpL1 promoter was found to be overlapped by an inverted repeat structure identical to the conserved CIRCE element, indicating that clpL1 belongs to the HrcA regulon in L. rhamnosus. No consensus binding sites for HrcA or CtsR could be identified in the clpL2 promoter region. Interestingly, the clpL2 gene was found to be surrounded by truncated transposase genes and flanked by inverted repeat structures nearly identical to the terminal repeats of the ISLpl1 from L. plantarum HN38. Furthermore, clpL2 was shown to be mobilized during prolonged cultivation at elevated temperature. The presence of a gene almost identical to clpL2 in L. plantarum and its absence in other L. rhamnosus strains suggest that the L. rhamnosus E-97800 has acquired the clpL2 gene via horizontal transfer. No change in the stress tolerance of the ClpL2-deficient derivative of E-97800 compared to the parental strain was observed.

* Corresponding author. Mailing address: Division of Microbiology and Epidemiology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, 00014 University of Helsinki, Helsinki, Finland. Phone: (358) 9 19 15 70 57. Fax: (358) 9 19 15 70 33. E-mail: pekka.varmanen{at}helsinki.fi.

Applied and Environmental Microbiology, April 2005, p. 2061-2069, Vol. 71, No. 4
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.4.2061-2069.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Wall, T., Bath, K., Britton, R. A., Jonsson, H., Versalovic, J., Roos, S. (2007). The Early Response to Acid Shock in Lactobacillus reuteri Involves the ClpL Chaperone and a Putative Cell Wall-Altering Esterase. Appl. Environ. Microbiol. 73: 3924-3935 [Abstract] [Full Text]  


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