Azide-Resistant Mutants of Escherichia coli Alter the SecA Protein, an Azide-Sensitive Component of the Protein Export Machinery

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 87; no. 21; pp. 8227 - 8231
• Main Authors: Oliver, Donald B., Cabelli, Robert J., Dolan, Katherine M., Jarosik, Gregory P.
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01-11-1990; National Acad Sciences
• Subjects: Adenosine triphosphatases; Adenosine Triphosphatases - genetics; Alleles; Azides; Azides - pharmacology; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Cell Membrane - metabolism; Chromosome Mapping; DNA; Drug Resistance, Microbial - genetics; Escherichia coli - drug effects; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins; Fundamental and applied biological sciences. Psychology; Genes, Bacterial; Genetic Complementation Test; Genetic mutation; Genetics; Membrane Transport Proteins; Microbiology; Mutation; P branes; Plasmids; Protein precursors; Protein transport; SEC Translocation Channels; Sodium; Sodium Azide; Genetic mapping; Translocation; Nucleotide sequence; Organic azide; ATPase; Escherichia coli; Biological transport; Proteins; Resistance; Allele; Bacteria; Mutation; Enterobacteriaceae
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.87.21.8227

Escherichia coli azi mutants, whose growth is resistant to millimolar concentrations of sodium azide, were among the earliest E. coli mutants isolated. Genetic complementation, mapping, and DNA sequence analysis now show that these mutations are alleles of the secA gene, which is essential for protein export across the E. coli plasma membrane. We have found that sodium azide is an extremely rapid and potent inhibitor of protein export in vivo and that azi mutants are more resistant to such inhibition. Furthermore, SecA-dependent in vitro protein translocation and ATPase activities are inhibited by sodium azide, and SecA protein prepared from an azi mutant strain is more resistant to such inhibition. These studies point to the utility of specific inhibitors of protein export, such as sodium azide, in facilitating the dissection of the function of individual components of the protein export machinery.