Characterization of the chromosomal aac(6')-Ic gene from Serratia marcescens.
The DNA sequence of the chromosomal aac(6')-Ic gene from Serratia marcescens, which had been previously cloned (H. M. Champion, P. M. Bennett, D. A. Lewis, and D. S. Reeves, J. Antimicrob. Chemother. 22:587-596, 1988) was determined. High-pressure liquid chromatographic analysis of extracts prepared from Escherichia coli carrying the chromosomal aac(6')-Ic gene on a plasmid confirmed the presence of 6'-N-acetyltransferase activity in this strain, which was suggested by the aminoglycoside resistance profile. DNA sequence analysis of the cloned 2,057-bp PstI fragment revealed several regions of homology to previously characterized sequences from GenBank, including the rpoD and tRNA-2 genes of E. coli. Subcloning experiments confirmed the coding sequence of the aac(6')-Ic gene to be at positions 1554 to 1992. The predicted amino acid sequence of the AAC(6')-Ic protein suggested that it was the third member of a family of AAC(6') proteins which included a coding region identified between the aadB and aadA genes of Tn4000 and an AAC(6') protein encoded by pUO490, which was isolated from Enterobacter cloacae. Primer extension analysis suggested that the -35 region of the aac(6')-Ic promoter overlapped a large palindromic sequence which may be involved in the regulation of the aac(6')-Ic gene. Hybridization experiments utilizing a restriction fragment from the aac(6')-Ic gene showed that all S. marcescens organisms carried this gene whether or not the AAC(6')-I resistance profile was expressed. Organisms other than Serratia spp. did not hybridize to this probe.
Schering-Plough Research Institute, Bloomfield, New Jersey 07003.
K J
KJ
Shaw
P N
PN
Rather
F J
FJ
Sabatelli
P
P
Mann
H
H
Munayyer
R
R
Mierzwa
G L
GL
Petrikkos
R S
RS
Hare
G H
GH
Miller
P
P
Bennett
P
P
Downey
D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D002876:Chromosomes, Bacterial; D015342:DNA Probes; D004269:DNA, Bacterial / Q000235:genetics; D006824:Hybridization, Genetic; D008969:Molecular Sequence Data; D010957:Plasmids; D012150:Polymorphism, Restriction Fragment Length; D012705:Serratia / Q000235:genetics* / Q000648:ultrastructure
D015342:DNA Probes; D004269:DNA, Bacterial