PT  - JOURNAL ARTICLE
AU  - Weng, Shu-Fen
AU  - Lin, Juey-Wen
AU  - Chen, Chih-Hung
AU  - Chen, Yih-Yuan
AU  - Tseng, Yi-Hsuan
AU  - Tseng, Yi-Hsiung
TI  - Constitutive Expression of a Chromosomal Class A (BJM Group 2) β-Lactamase in <em>Xanthomonas campestris</em>
AID  - 10.1128/AAC.48.1.209-215.2004
DP  - 2004 Jan 01
TA  - Antimicrobial Agents and Chemotherapy
PG  - 209--215
VI  - 48
IP  - 1
4099  - http://aac.asm.org/content/48/1/209.short
4100  - http://aac.asm.org/content/48/1/209.full
SO  - Antimicrob. Agents Chemother.2004 Jan 01; 48
AB  - Sequencing of the upstream region of the β-lactamase gene from Xanthomonas campestris pv. campestris 11 (blaXCC-1) revealed the cognate ampR1 gene (289 amino acids, 31 kDa). It runs divergently from blaXCC-1 with a 100-bp intergenic region (IG) containing partially overlapped promoters with structural features typical of the bla-ampR IG. The deduced AmpR1 protein shows significant identity in amino acid sequence and conserved motifs with AmpR proteins of other species, e.g., of Pseudomonas aeruginosa (58.2% amino acid identity). Results of insertional mutation, complementation tests, and β-lactamase assays suggested that expression of blaXCC-1 was constitutive and dependent on AmpR1. Four bla genes and two ampR genes are present in the fully sequenced X. campestris pv. campestris ATCC 33913 genome, with XCC3039 and XCC3040 considered the analogues of blaXCC-1 and ampR1, respectively. An ampR1 homologue was detected by Southern hybridization in the ampicillin-resistant Xanthomonas strains, which appear to express β-lactamase constitutively. Although the significance remains to be studied, constitutive expression of β-lactamase by a widespread bacterial genus raises environmental concerns regarding the dissemination of resistance genes.