AiiM, a Novel Class of N-Acylhomoserine Lactonase from the Leaf-Associated Bacterium Microbacterium testaceum

• Published in: Applied and Environmental Microbiology 2010-04, Vol.76 (8), p.2524-2530
• Main Authors: Wang, Wen-Zhao, Morohoshi, Tomohiro, Ikenoya, Masashi, Someya, Nobutaka, Ikeda, Tsukasa
• Format: Article
• Language: English
• Subjects: 4-Butyrolactone - analogs & derivatives; 4-Butyrolactone - metabolism; Actinobacteria; Actinomycetales - enzymology; Actinomycetales - genetics; Actinomycetales - isolation & purification; Antibiosis; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Carbon; Carboxylic Ester Hydrolases - genetics; Carboxylic Ester Hydrolases - metabolism; Chromatography, High Pressure Liquid; Cloning, Molecular; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression; Genomic Library; Gram-negative bacteria; Leaves; Microbiology; Molecular Sequence Data; Molecules; Pectobacterium carotovorum - genetics; Plant Diseases - microbiology; Plant Leaves - microbiology; Plant Microbiology; Potatoes; Proteins; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Solanum tuberosum - microbiology
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.02738-09

N-Acylhomoserine lactones (AHLs) are used as quorum-sensing signal molecules by many Gram-negative bacteria. We have reported that Microbacterium testaceum StLB037, which was isolated from the leaf surface of potato, has AHL-degrading activity. In this study, we cloned the aiiM gene from the genomic library of StLB037, which has AHL-degrading activity and shows high homology with the α/β hydrolase fold family from ACTINOBACTERIA: Purified AiiM as a maltose binding fusion protein showed high degrading activity of AHLs with both short- and long-chain AHLs with or without substitution at carbon 3. High-performance liquid chromatography analysis revealed that AiiM works as an AHL lactonase that catalyzes AHL ring opening by hydrolyzing lactones. In addition, expression of AiiM in the plant pathogen Pectobacterium carotovorum subsp. carotovorum reduced pectinase activity markedly and attenuated soft rot symptoms on potato slices. In conclusion, this study indicated that AiiM might be effective in quenching quorum sensing of P. carotovorum subsp. carotovorum.