A staphylococcal multidrug resistance gene product is a member of a new protein family
The complete nucleotide sequence (321 bp) of smr (staphylococcal multidrug resistance), a gene coding for efflux-mediated multidrug resistance of Staphylococcus aureus, was determined by using two different plasmids as DNA templates. The smr gene product (identical to products of ebr and qacC/ D gen...
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Published in | Plasmid Vol. 27; no. 2; pp. 119 - 129 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
San Diego, CA
Elsevier Inc
01.03.1992
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | The complete nucleotide sequence (321 bp) of
smr (staphylococcal
multidrug resistance), a gene coding for efflux-mediated multidrug resistance of
Staphylococcus aureus, was determined by using two different plasmids as DNA templates. The
smr gene product (identical to products of
ebr and
qacC/
D genes) was shown to be homologous to a new family of small membrane proteins found in
Escherichia coli, Pseudomonas aeruginosa, Agrobacterium tumefaciens, and
Proteus vulgaris. The
smr gene was subcloned and expressed in
S. aureus and
E. coli and its ability to confer the multidrug resistant phenotype was demonstrated for two different lipophilic cation classes: phosphonium derivatives and quarternary amines. Expression of
smr gene leads to the efflux of tetraphenylphosphonium and to a net decrease in the uptake of lipophilic cations. The deduced polypeptide sequence (107 amino acid residues, 11,665 kDa) has 46% hydrophobic residues (Phe, Ile, Leu, and Val) and 20% hydroxylic residues (Ser and Thr). Four transmembrane segments are predicted for
smr gene product. Of the charged amino acid residues, only Glu 13 is located in a transmembrane segment. This Glu 13 is conserved in all members of the family of small membrane proteins. We propose a mechanism whereby exchange of protons at the Glu 13 is a key in the efflux of the lipophilic cation. This mechanism includes the idea that protons are transported to the Glu 13 via an appropriate chain of hydroxylic residues in the transmembrane segments of Smr. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0147-619X 1095-9890 |
DOI: | 10.1016/0147-619X(92)90012-Y |