AmpDI is involved in expression of the chromosomal L1 and L2 beta-lactamases of Stenotrophomonas maltophilia.
Two ampD homologues, ampD(I) and ampD(II), of Stenotrophomonas maltophilia have been cloned and analyzed. Comparative genomic analysis revealed that the genomic context of the ampD(II) genes is quite different, whereas that of the ampD(I) genes is more conserved in S. maltophilia strains. The ampD system of S. maltophilia is distinct from that of the Enterobacteriaceae and Pseudomonas aeruginosa in three respects. (i) AmpD(I) of S. maltophilia is not encoded in an ampDE operon, in contrast to what happens in the Enterobacteriaceae and P. aeruginosa. (ii) The AmpD systems of the Enterobacteriaceae and P. aeruginosa are generally involved in the regulation of ampR-linked ampC gene expression, while AmpD(I) of S. maltophilia is responsible for the regulation of two intrinsic beta-lactamase genes, of which the L2 gene, but not the L1 gene, is linked to ampR. (iii) S. maltophilia exhibits a one-step L1 and L2 gene derepression model involving ampD(I), distinct from the two- or three-step derepression of the Enterobacteriaceae and P. aeruginosa. Moreover, the ampD(I) and ampD(II) genes are constitutively expressed and not regulated by the inducer and AmpR protein, and the expression of ampD(II) is weaker than that of ampD(I). Finally, AmpD(II) is not associated with the derepression of beta-lactamases, and its role in S. maltophilia remains unclear.
Yang
Tsuey-Ching
TC
Department of Medical Laboratory Science and Biotechnology, China Medical University, 91 Hsueh-Shih Rd., Taichung, Taiwan, Republic of China. tcyang@mail.cmu.edu.tw
Huang
Yi-Wei
YW
Hu
Rouh-Mei
RM
Huang
Shao-Cheng
SC
Lin
Yu-Tzu
YT
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D016680:Genome, Bacterial / Q000235:genetics / Q000502:physiology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020615:Stenotrophomonas maltophilia / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C088032:beta-lactamase L1; C425104:beta-lactamase L2; D001618:beta-Lactamases