Characterization of acyl-homoserine lactonase gene from Brevibacillus brevis strain B37

Abstract

Acyl-homoserine lactonase (EC 3.1.1.25) is a metallo-betalactamase, specifically hydrolyzed N-acyl-homoserine lactones (AHL) secreted by Gram-negative bacteria. AHL lactonase has been reported as a potential substitute for synthetic anti-bacterial, such as reduce the severity of plant diseases caused by Xanthomonas campestris pv. campestris, and Pectobacterium catrotovorum. The exploration of lactonase producing organisms has been widely reported. AHL-lactonase is produced by Bacillaceae bacteria such as Bacillus thuringiensis, B. cereus, and B. antrachis. AHL-lactonase produced by Bacillaceae bacteria was translated from aiiA gene. In our previous study, aiiA novel gene was detected in Brevibacillus brevis B37 but has not been characterized. This study aimed to clone aiiA gene isolated from B.brevis B37 by polymerase chain reaction (PCR) with a pair of degenerated primers, to reveal homology comparison withothers aiiA genes and amino acids, to express aiiA gene in Escherichia coli BL21 (DE3), and also to assay quorum quencherability. The aiiA gene was successfully isolated with 753 bp and 250 amino acids. The aiiA gene and the AiiA protein fromB.brevis B37 had high similarity with aiiA and AiiA from B. thuringiensis group. The deduced amino acid sequencecontained conserved sequence region 103SHLHFDH109 and 166TPGHTPGH173 as characteristic of the metallo betalactamasefamily. Additionally, the aiiAB37 gene was expressed in E. coli BL21 (DE3) and the expressed AiiA protein could attenuate the expression of violacein produce by Chromobacterium violaceum and decrease the expression of soft rot symptom caused by Dickeya dadantii.