The Aminoglycoside 6′-N-Acetyltransferase Type Ib Encoded by Tn1331 Is Evenly Distributed within the Cell's Cytoplasm
AUTOR(ES)
Dery, Ken J.
FONTE
American Society for Microbiology
RESUMO
The multiresistance transposon Tn1331, which mediates resistance to several aminoglycosides and β-lactams, includes the aac(6′)-Ib, aadA1, blaOXA-9, and blaTEM-1 genes. The nucleotide sequence of aac(6′)-Ib includes a region identical to that of the blaTEM-1 gene. This region encompasses the promoter and the initiation codon followed by 15 nucleotides. Since there were three possible translation initiation sites, the amino acid sequence at the N terminus of the aminoglycoside 6′-N-acetyltransferase type Ib [AAC(6′)-Ib] was determined and was found to be SIQHF. This result indicated that aac(6′)-Ib includes a translational fusion: the first five amino acids of the leader peptide of the TEM β-lactamase are fused to the rest of the AAC(6′)-Ib protein. This gene fusion could have formed during the genesis of Tn1331 as a consequence of the generation of a 520-nucleotide duplication (M. E. Tolmasky, Plasmid 24:218-226, 1990). An identical gene isolated from a Serratia marcescens strain has been previously described (G. Tran van Nhieu and E. Collatz, J. Bacteriol. 169:5708-5714, 1987). Extraction of the periplasmic proteins of E. coli harboring aac(6′)-Ib by spheroplast formation showed that most of the AAC(6′)-Ib protein is present in the cytoplasm. A genetic fusion to phoA confirmed these results. AAC(6′)-Ib was shown to be evenly distributed inside the cell's cytoplasm by fluorescent microscopy with an AAC(6′)-Ib-cyan fluorescent protein fusion.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=182613Documentos Relacionados
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