PMID:12384340

Citation	Sánchez, P, Alonso, A and Martinez, JL (2002) Cloning and characterization of SmeT, a repressor of the Stenotrophomonas maltophilia multidrug efflux pump SmeDEF. Antimicrob. Agents Chemother. 46:3386-93
Abstract	We report on the cloning of the gene smeT, which encodes the transcriptional regulator of the Stenotrophomonas maltophilia efflux pump SmeDEF. SmeT belongs to the TetR and AcrR family of transcriptional regulators. The smeT gene is located upstream from the structural operon of the pump genes smeDEF and is divergently transcribed from those genes. Experiments with S. maltophilia and the heterologous host Escherichia coli have demonstrated that SmeT is a transcriptional repressor. S1 nuclease mapping has demonstrated that expression of smeT is driven by a single promoter lying close to the 5' end of the gene and that expression of smeDEF is driven by an unique promoter that overlaps with promoter PSMET: The level of expression of smeT is higher in smeDEF-overproducing S. maltophilia strain D457R, which suggests that SmeT represses its own expression. Band-shifting assays have shown that wild-type strain S. maltophilia D457 contains a cellular factor(s) capable of binding to the intergenic smeT-smeD region. That cellular factor(s) was absent from smeDEF-overproducing S. maltophilia strain D457R. The sequence of smeT from D457R showed a point mutation that led to a Leu166Gln change within the SmeT protein. This change allowed overexpression of both smeDEF and smeT in D457R. It was noteworthy that expression of wild-type SmeT did not fully complement the smeT mutation in D457R. This suggests that the wild-type protein is not dominant over the mutant SmeT.
Links	PubMed PMC128709
Keywords	Amino Acid Sequence; Base Sequence; Chromosome Mapping; Cloning, Molecular; DNA, Bacterial/genetics; Drug Resistance, Multiple, Bacterial; Electrophoretic Mobility Shift Assay; Genes, Bacterial/genetics; Histidine/metabolism; Molecular Sequence Data; Plasmids/genetics; RNA, Bacterial/genetics; Repressor Proteins/genetics; Reverse Transcriptase Polymerase Chain Reaction; Stenotrophomonas maltophilia/genetics; Stenotrophomonas maltophilia/metabolism; Transcription, Genetic; beta-Galactosidase/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
STEMA:Q8KLP4		GO:0003714: transcription corepressor activity	ECO:0000315:		F		Fig 4 - shows introduction of smeT gene to both wild type and mutant reduced SmeF expression	complete CACAO 8772

References

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