Acquisition of azide-resistance by elevated SecA ATPase activity confers azide-resistance upon cell growth and protein translocation in Bacillus subtilis.
We isolated four azide-resistant secA mutants of Bacillus subtilis and found that all of them were the result of a single amino acid replacement of threonine 128 of SecA by alanine or isoleucine. In the presence of 1.5 mM sodium azide, cell growth and protein translocation of the wild-type strain were completely inhibited, but those of the azide-resistant mutant strains were not. Wild-type and two mutant SecA proteins were purified. Both the basal level and the elevated ATPase activity of the mutant SecA proteins were threefold higher than those of the wild-type SecA. The elevated ATPase activity of the SecA mutants was reduced upon the addition of 1.5 mM sodium azide by only 5-10% as compared with 40% for that of the wild-type. These results indicate that the elevated ATPase activity of the SecA mutants is resistant to sodium azide and that is also required for the protein translocation process of B. subtilis.
Nakane
A
A
Institute of Biological Sciences, University of Tsukuba, Ibaraki, Japan.
Takamatsu
H
H
Oguro
A
A
Sadaie
Y
Y
Nakamura
K
K
Yamane
K
K
D000251:Adenosine Triphosphatases / Q000096:biosynthesis / Q000378:metabolism*; D000409:Alanine; D000595:Amino Acid Sequence; D001386:Azides / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport; D002455:Cell Division / Q000187:drug effects; D017931:DNA Primers; D004352:Drug Resistance, Microbial; D029968:Escherichia coli Proteins; D007532:Isoleucine; D007700:Kinetics; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D019810:Sodium Azide; D013912:Threonine
D001386:Azides; D001426:Bacterial Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; D007532:Isoleucine; D013912:Threonine; D019810:Sodium Azide; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins; D000409:Alanine