title: An N-acyl homoserine lactone synthase in the ammonia-oxidizing bacterium Nitrosospira multiformis.
abstract: The chemolithoautotrophic bacterium Nitrosospira multiformis is involved in affecting the process of nitrogen cycling. Here we report the existence and characterization of a functional quorum sensing signal synthase in N. multiformis. One gene (nmuI) playing a role in generating a protein with high levels of similarity to N-acyl homoserine lactone (AHL) synthase protein families was identified. Two AHLs (C14-AHL and 3-oxo-C14-AHL) were detected using an AHL biosensor and liquid chromatography-mass spectrometry (LC-MS) when nmuI, producing a LuxI homologue, was introduced into Escherichia coli. However, by extracting N. multiformis culture supernatants with acidified ethyl acetate, no AHL product was obtained that was capable of activating the biosensor or being detected by LC-MS. According to reverse transcription-PCR, the nmuI gene is transcribed in N. multiformis, and a LuxR homolog (NmuR) in this ammonia-oxidizing strain showed great sensitivity to long-chain AHL signals by solubility assay. A degradation experiment demonstrated that the absence of AHL signals might be attributed to the possible AHL-inactivating activities of this strain. To summarize, an AHL synthase gene (nmuI) acting as a long-chain AHL producer has been found in a chemolithotrophic ammonia-oxidizing microorganism, and the results provide an opportunity to complete the knowledge of the regulatory networks in N. multiformis.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Gao
authors.forename: Anzhou
authors.initials: A
authors.lastname: Ma
authors.forename: Xuliang
authors.initials: X
authors.lastname: Zhuang
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Zhuang
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism*; D000595:Amino Acid Sequence; D015374:Biosensing Techniques; D002853:Chromatography, Liquid; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D008025:Ligases / Q000235:genetics / Q000302:isolation & purification*; D013058:Mass Spectrometry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D043369:Nitrosomonadaceae / Q000201:enzymology*; D011487:Protein Conformation; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D054742:Acyl-Butyrolactones; D004269:DNA, Bacterial; D008025:Ligases; C449816:N-acylhomoserine lactone synthase