title: Functional analysis of three AHL autoinducer synthase genes in Mesorhizobium loti reveals the important role of quorum sensing in symbiotic nodulation.
abstract: One of the most important signal transduction pathways in bacteria, quorum sensing, is involved in many regulatory circuits in rhizobia, especially in the control of communication between rhizobia and their plant hosts. In this study, we identified 3 autoinducer synthase genes - mrlI1, mrlI2, and mrlI3 - in Mesorhizobium loti NZP 2213. We found that MrlI1 and MrlI2 could synthesize distinct N-acyl homoserine lactone (AHL) autoinducers in rich medium cultures, and the expression of mrlI1 was shown to be growth-phase-dependent. MrlI3 did not produce any detectable AHL molecules under the culture conditions tested. To investigate whether these AHL synthases affect nodulation, we examined the nodulation of AHL-deficient mutants on their native plant host Lotus corniculatus and found that the efficiency of nodulation of bacteria with mutations of any of these 3 synthase genes was reduced, suggesting that quorum sensing systems in M. loti may play an important role in successful establishment of rhizobium-legume symbiosis.
authors.affiliation: Department of Microbiology, Nanjing Agricultural University, Nanjing, China.
authors.forename: Menghua
authors.initials: M
authors.lastname: Yang
authors.forename: Kejing
authors.initials: K
authors.lastname: Sun
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Ruifu
authors.initials: R
authors.lastname: Yang
authors.forename: Zengtao
authors.initials: Z
authors.lastname: Zhong
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
mesh_terms: D054742:Acyl-Butyrolactones / Q000378:metabolism; D020561:Alphaproteobacteria / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D000070116:Lotus / Q000382:microbiology / Q000502:physiology; D053038:Quorum Sensing; D053204:Root Nodules, Plant / Q000382:microbiology* / Q000502:physiology; D013559:Symbiosis
chemical_list: D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; D008025:Ligases; C449816:N-acylhomoserine lactone synthase