CLONING, NUCLEOTIDE-SEQUENCE AND STRUCTURAL-ANALYSIS OF THE CLOSTRIDIUM-ACETOBUTYLICUM DNAJ GENE

The complete dnaJ gene of Clostridium acetobutylicum was isolated by c hromosome walking using the previously cloned 5' end of the gene as a probe. Nucleotide sequencing of a positively reacting 2.2-kb HincII fr agment, contained in the recombinant plasmid pKG4, revealed that the r eading frame of the dnaJ gene of C. acetobutylicum consists of 1125 bp , encoding a protein of 374 amino acids with a calculated M(r) of 4037 6 and an isoelectric point of 9.54. The deduced amino acid sequence sh owed high similarity to the DnaJ proteins of other bacteria (e.g. Esch erichia coli, Bacillus subtilis) as well as of an archaeon (Methanosar cina mazei) and to the corresponding proteins of eukaryotes (Saccharom yces cerevisiae, Home sapiens). The areas of similarity included a con served N-terminal domain of about 70 amino acids, a glycine-rich regio n of about 30 residues, and a central domain containing four repeats o f a CXXCXGXG motif, whereas the C-terminal domain was less conserved. Northern (RNA) blot analysis indicated that dnaJ is induced by heat sh ock and that it is part of the dnaK operon of C. acetobutylicum. The 5 ' end (901 bp) of another gene (orfB), downstream of dnaJ and not heat -inducible, showed no significant similarity to other sequences availa ble in EMBL and GenBank databases.