Characterization of an LysR family protein, SmeR from Serratia marcescens S6, its effect on expression of the carbapenem-hydrolyzing beta-lactamase Sme-1, and comparison of this regulator with other beta-lactamase regulators.
AUTOR(ES)
Naas, T
RESUMO
Serratia marcescens S6 produces a chromosomally encoded carbapenem-hydrolyzing class A beta-lactamase, Sme-1 (T. Naas, L. Vandel, W. Sougakoff, D. M. Livermore, and P. Nordmann, Antimicrob. Agents Chemother. 38:1262-1270, 1994). Upstream from smeA we identified a second open reading frame (EMBL accession number Z30237). This encodes a 33.1-kDa protein, SmeR, which has a high degree of homology with NmcR, the LysR regulatory protein of the only other sequenced carbapenem-hydrolyzing class A beta-lactamase, NmcA from Enterobacter cloacae NOR-1. It is weakly related to AmpR of the chromosomal cephalosporinase regulatory systems described in E. cloacae, Yersinia enterocolitica, Citrobacter freundii, and Pseudomonas aeruginosa and is very weakly related to other LysR-type regulators of class A beta-lactamases. SmeR is a weakly positive regulator for Sme-1 expression in the absence of or in the presence of beta-lactam inducers. The -35 and -10 regions of smeR are in the opposite orientations and are face-to-face relative to the smeA promoter. SmeR acts similarly to NmcR and not as the AmpR regulators described for class C beta-lactamase systems. SmeR is a weak inducer in the absence or presence of beta-lactams. As was found for the AmpC-AmpR and NmcA-NmcR systems, a putative SmeR-binding site was present upstream from the beta-lactamase gene promoter regions. beta-Galactosidase activity from a smeR-lacZ translational fusion was expressed constitutively and decreased in the presence of SmeR from a coresident plasmid, suggesting that SmeR is autogeneously controlled. Finally, beta-lactams did not affect the expression of SmeR, which is the second regulator of a class A carbapenem-hydrolyzing beta-lactamase to be identified.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=162596Documentos Relacionados
- Cloning and sequence analysis of the gene for a carbapenem-hydrolyzing class A beta-lactamase, Sme-1, from Serratia marcescens S6.
- Analysis of a carbapenem-hydrolyzing class A beta-lactamase from Enterobacter cloacae and of its LysR-type regulatory protein.
- SME-Type Carbapenem-Hydrolyzing Class A β-Lactamases from Geographically Diverse Serratia marcescens Strains
- Carbapenem-hydrolyzing beta-lactamases.
- Biochemical properties of a carbapenem-hydrolyzing beta-lactamase from Enterobacter cloacae and cloning of the gene into Escherichia coli.