Format

Send to

Choose Destination
See comment in PubMed Commons below
Cell Stress Chaperones. 2007 Summer;12(2):123-31.

Homologous cpn60 genes in Rhizobium leguminosarum are not functionally equivalent.

Author information

  • 1School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK.

Abstract

Many bacteria possess 2 or more genes for the chaperonin GroEL and the cochaperonin GroES. In particular, rhizobial species often have multiple groEL and groES genes, with a high degree of amino-acid similarity, in their genomes. The Rhizobium leguminosarum strain A34 has 3 complete groE operons, which we have named cpn.1, cpn.2 and cpn.3. Previously we have shown the cpn. 1 operon to be essential for growth, but the two other cpn operons to be dispensable. Here, we have investigated the extent to which loss of the essential GroEL homologue Cpn60.1 can be compensated for by expression of the other two GroEL homologues (Cnp60.2 and Cpn60.3). Cpn60.2 could not be overexpressed to high levels in R. leguminosarum, and was unable to replace Cpn60.1. A strain that overexpressed Cpn60.3 grew in the absence of Cpn60.1, but the complemented strain displayed a temperature-sensitive phenotype. Cpn60.1 and Cpn60.3, when coexpressed in Escherichia coli, preferentially selfassembled rather than forming mixed heteroligomers. We conclude that, despite their high amino acid similarity, the GroEL homologues of R. leguminosarum are not functionally equivalent in vivo.

PMID:
17688191
PMCID:
PMC1949324
[PubMed - indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for PubMed Central
    Loading ...
    Write to the Help Desk