title: Cloning and identification of lpsH, a novel gene playing a fundamental role in symbiotic nitrogen fixation of Mesorhizobium huakuii.
abstract: Mesorhizobium huakuii 7653R forms a symbiotic relationship with Astragalus sinicus to produce nitrogen-fixing root nodules under nitrogen-limiting conditions. By screening its transposon-inserted mutant library, a mutation in the lpsH gene was found to form pseudonodules on A. sinicus. Its effect was further confirmed by double-crossover mutant HK242. DNA sequence analysis revealed that the lpsH gene encodes a deduced protein of 397 amino acids with a predicted molecular mass of 43.6 kD. LpsH contains a putative signal peptide, 11 transmembrane helices, and an O-antigen polymerase domain, which locates on the periplasmic membrane and is necessary to lipopolysaccharide synthesis. Plant studies showed that the lpsH gene mutant formed ineffective nodules, and this symbiotic phenotype was linked to abnormal nodule development.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070, Wuhan, China.
authors.forename: Guojun
authors.initials: G
authors.lastname: Cheng
authors.forename: Youguo
authors.initials: Y
authors.lastname: Li
authors.forename: Bo
authors.initials: B
authors.lastname: Xie
authors.forename: Chengyun
authors.initials: C
authors.lastname: Yang
authors.forename: Junchu
authors.initials: J
authors.lastname: Zhou
mesh_terms: D020561:Alphaproteobacteria / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D027883:Astragalus Plant / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D019295:Computational Biology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013559:Symbiosis / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D008565:Membrane Proteins