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- Title
Identification of the critical role of Tyr-194 in the catalytic activity of a novel N-acyl-homoserine lactonase from marine Bacillus cereus strain Y2.
- Authors
Lu, X; Yuan, Y; Xue, X-L; Zhang, G-P; Zhou, S-N
- Abstract
Enzymatic disruption of quorum-sensing (QS) pathways in pathogenic organisms is a promising anti-infection therapeutic strategy. AHL-lactonase, a potent tool for biocontrol, can hydrolyze QS signal molecule N-acyl-homoserine lactones (AHLs) into inactive products, thereby blocking the QS systems. A marine bacterial isolate Y2, identified as a Bacillus cereus subsp., was found capable of inactivating AHLs. The aiiA gene encoding the AHL-degrading enzyme from bacterial strain Y2 was cloned and expressed in Escherichia coli. The 28-kDa recombinant Y2-AiiA protein was purified and showed strong AHL-degrading activity. Sequence comparisons of Y2-aiiA with known AHL-lactonases revealed high identities in the deduced amino-acid sequences. Functional determination of a potential catalytic residue Tyr-194 of AHL-lactonases was performed by site-directed mutagenesis. As judged by AHL-degrading bioassay, substitution of Tyr-194 with Ala resulted in a dramatic decrease of activity compared with wild-type (WT) recombinant Y2-AiiA, although the expression level of the mutated Y2-AiiA protein was equivalent to that of WT Y2-AiiA. These results suggested that the conserved residue Tyr-194 is critical for catalytic function of the novel AHL-lactonase.
- Publication
Current microbiology, 2006, Vol 53, Issue 4, p346
- ISSN
0343-8651
- Publication type
Journal Article
- DOI
10.1007/s00284-006-0224-1