title: Genetic analysis of zwittermicin A resistance in Escherichia coli: effects on membrane potential and RNA polymerase.
abstract: Zwittermicin A is a novel aminopolyol antibiotic that represents a new structural class of antibiotic and has diverse biological activities, including the suppression of plant disease and the ability to inhibit prokaryotic and eukaryotic cells. To enhance our fundamental understanding and applications of zwittermicin A, we elucidated mechanisms of zwittermicin A resistance in Escherichia coli. Two classes of zwittermicin A-resistant mutants of E. coli were selected and characterized. One class included mutants altered in hemA, hemB, hemL, ubi, cydAB or atp, which were defective in generating a proton motive force (PMF) and resistant to aminoglycosides. The mutant analysis, coupled with physiological data, indicated an association between the electrical membrane potential (deltapsi) component of PMF and zwittermicin A sensitivity. A second class of zwittermicin A-resistant mutants was aminoglycoside sensitive and was affected in rpoB and rpoC, genes that encode subunits of RNA polymerase. The rpoB and rpoC mutants suggested that zwittermicin A might inhibit transcription, DNA replication, DNA gyrase or topoisomerase I; however, we found no further evidence to support any of these as the target for zwittermicin A. This study elucidated the genetic mechanisms of zwittermicin A resistance in E. coli. The results suggest that deltapsi drives zwittermicin A uptake, and that, unlike other antibiotics for which resistance maps in rpoB or rpoC, zwittermicin A does not cause the rapid cessation of DNA or RNA synthesis, suggesting a unique mechanism of antibiosis.
authors.affiliation: Department of Bacteriology, University of Wisconsin, Madison 53706, USA.
authors.forename: E V
authors.initials: EV
authors.lastname: Stabb
authors.forename: J
authors.initials: J
authors.lastname: Handelsman
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D003573:Cytochrome b Group; D003580:Cytochromes / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000096:biosynthesis; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism*; D004352:Drug Resistance, Microbial; D045222:Electron Transport Chain Complex Proteins; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D006418:Heme / Q000096:biosynthesis; D008564:Membrane Potentials; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010455:Peptides; D012329:RNA, Bacterial / Q000096:biosynthesis; D014451:Ubiquinone / Q000096:biosynthesis
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D003573:Cytochrome b Group; D003580:Cytochromes; D004269:DNA, Bacterial; D045222:Electron Transport Chain Complex Proteins; D029968:Escherichia coli Proteins; D010455:Peptides; D012329:RNA, Bacterial; D014451:Ubiquinone; C088290:zwittermicin A; D006418:Heme; D010088:Oxidoreductases; C040077:cytochrome bd terminal oxidase complex, E coli; C108570:beta' subunit of RNA polymerase; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit; D000251:Adenosine Triphosphatases