A novel fusidic acid resistance gene from Streptomyces lividans 66 encodes a highly specific esterase.
Resistance to fusidic acid in Streptomyces lividans is due to secretion of an extracellular enzyme (FusH) that converts the steroid antibiotic into an inactive derivative. NH2-terminal and several internal amino acid sequences were prepared from the purified enzyme. Using one of the deduced oligonucleotides to probe a subgenomic DNA library, the fusH gene was cloned and sequenced. Sequence analysis located an ORF which, owing to the presence of two putative start codons, indicates a predicted protein with 520 or 509 amino acids. A signal peptide was identified by aligning the deduced amino acids with the N-terminal sequence determined for the mature enzyme. The C-terminal part of the deduced FusH contains a region of three tandemly repeated stretches of 50 amino acids, which is preceded and followed by amino acids showing high homology with the repeats. FusH was found to share a GDS motif with some deduced esterases. S. lividans transformants carrying fusH on a multicopy vector synthesized high levels of FusH. Purified FusH cleaved equally well an acetyl, a thioacetyl or a formyl group from the 16 beta-position of fusidic acid and its derivatives. However, a propionyl group at the 16 beta-position was attacked with difficulty and a 16 alpha-acetyl group was not hydrolysed at all. These data indicate that FusH is a highly specific esterase. The fusH gene is widely distributed among streptomycetes that modify fusidic acid to its inactive lactone derivative.
von der Haar
Beate
B
Universitt Osnabrück, FB Biologie/Chemie, Barbarastraße 11, 49069 Osnabrück, Germany.
Walter
Stefan
S
Universitt Osnabrück, FB Biologie/Chemie, Barbarastraße 11, 49069 Osnabrück, Germany.
Schwäpenheer
Susanne
S
Universitt Osnabrück, FB Biologie/Chemie, Barbarastraße 11, 49069 Osnabrück, Germany.
Schrempf
Hildgund
H
Universitt Osnabrück, FB Biologie/Chemie, Barbarastraße 11, 49069 Osnabrück, Germany.
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D003001:Cloning, Molecular; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004950:Esterases / Q000235:genetics*; D005672:Fusidic Acid / Q000494:pharmacology*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013302:Streptomyces / Q000187:drug effects / Q000235:genetics*
D000900:Anti-Bacterial Agents; D005672:Fusidic Acid; D004950:Esterases