Suppression of the growth and export defects of an Escherichia coli secA(Ts) mutant by a gene cloned from Bacillus subtilis.
A gene library of Bacillus subtilis chromosomal DNA was screened for genes capable of reverting the growth defects of the Escherichia coli secA51(Ts) mutant at 42 degrees C. A B. subtilis gene, designated csaA, was found to phenotypically suppress not only the growth defects of the E. coli mutant, but also to relieve the detrimental accumulation of precursors of exported proteins. The csaA gene encoded a protein of 15 kDa (137 amino acids) and was likely to be the distalmost member of an operon. No similarity to csaA was found among DNA or protein sequences deposited in databases. In contrast to other homologous or heterologous suppressors of the E. coli secA51(Ts) mutation, the csaA gene did not exert pleiotropic effects on either the E. coli secY24(Ts) or lep9(Ts) mutations. However, it restored the ability of a SecB-deficient mutant to grow on complex medium. It is proposed that CsaA serves as a molecular chaperone for exported proteins or alternatively acts by stabilizing the SecA protein.
Müller
J
J
Institute for Microbiology and Experimental Therapy, Department of Microbial Genetics, Jena, FRG.
Walter
F
F
van Dijl
J M
JM
Behnke
D
D
D000251:Adenosine Triphosphatases / Q000235:genetics*; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D016153:Genes, Suppressor; D007700:Kinetics; D026901:Membrane Transport Proteins; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D010957:Plasmids; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D013696:Temperature
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D018832:Molecular Chaperones; D000069816:SEC Translocation Channels; C077891:CsaA protein, Bacillus subtilis; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins