Zwittermicin A is a novel aminopolyol antibiotic produced by Bacillus
cereus that is active against diverse bacteria and lower eukaryotes (L
. A. Silo-Suh, B. J. Lethbridge, S. J. Raffel, H. He, J. Clardy, and J
. Handelsman, Appl. Environ, Microbiol. 60:2023-2030, 1994), To identi
fy a determinant for resistance to zwittermicin A, we constructed a ge
nomic library from B. cereus UW85, which produces zwittermicin A, and
screened transformants of Escherichia coli DH5 alpha, which is sensiti
ve to zwittermicin A, for resistance to zwittermicin A, Subcloning and
mutagenesis defined a genetic locus, designated zmaR, on a 1.2-kb fra
gment of DNA that conferred zwittermicin A resistance on E, coli, A DN
A fragment containing zmaR hybridized to a corresponding fragment of g
enomic DNA from B. cereus UW85, Corresponding fragments were not detec
ted in mutants of B. cereus UW85 that were sensitive to zwittermicin A
, and the plasmids carrying zmaR restored resistance to the zwittermic
in A-sensitive mutants, indicating that zmaR was deleted in the zwitte
rmicin A-sensitive mutants and that zmaR is functional in B. cereus, S
equencing of the 1.2-kb fragment of DNA defined an open reading frame,
designated ZmaR, Neither the nucleotide sequence nor the predicted pr
otein sequence had significant similarity to sequences in existing dat
abases, Cell extracts from an E. call strain carrying zmaR contained a
43.5-kDa protein whose molecular mass and N-terminal sequence matched
those of the protein predicted by the zmaR sequence, The results demo
nstrate that we have isolated a gene, zmaR, that encodes a zwittermici
n A resistance determinant that is functional in both B, cereus and E.
coli.