Journal Article

Physiological consequences of the over-production of <i>E. coli</i> truncated molecular chaperone DnaJ

Salma Al-Herran and William Ashraf

in FEMS Microbiology Letters

Volume 162, issue 1, pages 117-122
Published in print May 1998 |
Published online January 2006 | e-ISSN: 1574-6968 | DOI: http://dx.doi.org/10.1111/j.1574-6968.1998.tb12987.x

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Abstract

In Escherichia coli one of the main molecular chaperones is DnaJ (hsp40) which mediates in a variety of highly conserved cellular process including protein folding reactions and assembly/disassembly of protein complexes. In this study we have investigated the toxicity of the over-production of DnaJ and two truncated polypeptides by examining growth rates, cell morphology and cell viability. Full-length DnaJ (1–375 amino acids) and truncated polypeptides, corresponding to the last 176 (containing the substrate binding domain) and 266 (containing the zinc finger-like domain) amino acids of the C-terminus of DnaJ, DnaJΔ1–199 and Δ1–108 respectively, were over-produced via IPTG induction. High levels of synthesis were determined by SDS-PAGE and Western blotting using anti-DnaJ antibodies. The over-production of full-length DnaJ resulted in a low degree of filamentation and a decrease in cell viability. However, over-production of DnaJ truncated polypeptides, especially DnaJΔ1–108, was bactericidal and resulted in a loss of viability and defective septation.

Keywords: Escherichia coli; Molecular chaperone; DnaJ; Overproduction

Journal Article.  1927 words.  Illustrated.

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