RRC ID 12246
Author Okazaki S, Okabe S, Higashi M, Shimoda Y, Sato S, Tabata S, Hashiguchi M, Akashi R, Göttfert M, Saeki K.
Title Identification and functional analysis of type III effector proteins in Mesorhizobium loti.
Journal Mol Plant Microbe Interact
Abstract Mesorhizobium loti MAFF303099, a microsymbiont of the model legume Lotus japonicus, possesses a cluster of genes (tts) that encode a type III secretion system (T3SS). In the presence of heterologous nodD from Rhizobium leguminosarum and a flavonoid naringenin, we observed elevated expression of the tts genes and secretion of several proteins into the culture medium. Inoculation experiments with wild-type and T3SS mutant strains revealed that the presence of the T3SS affected nodulation at a species level within the Lotus genus either positively (L. corniculatus subsp. frondosus and L. filicaulis) or negatively (L. halophilus and two other species). By inoculating L. halophilus with mutants of various type III effector candidate genes, we identified open reading frame mlr6361 as a major determinant of the nodulation restriction observed for L. halophilus. The predicted gene product of mlr6361 is a protein of 3,056 amino acids containing 15 repetitions of a sequence motif of 40 to 45 residues and a shikimate kinase-like domain at its carboxyl terminus. Homologues with similar repeat sequences are present in the hypersensitive-response and pathogenicity regions of several plant pathogens, including strains of Pseudomonas syringae, Ralstonia solanacearum, and Xanthomonas species. These results suggest that L. halophilus recognizes Mlr6361 as potentially pathogen derived and subsequently halts the infection process.
Volume 23(2)
Pages 223-34
Published 2010-2-1
DOI 10.1094/MPMI-23-2-0223
PMID 20064065
MeSH Bacterial Proteins / genetics Bacterial Proteins / metabolism* Lotus / microbiology Multigene Family / physiology* Open Reading Frames / physiology* Protein Structure, Tertiary / physiology Rhizobiaceae / genetics Rhizobiaceae / metabolism* Secretory Pathway / physiology* Sequence Homology, Amino Acid Symbiosis / physiology
IF 3.696
Times Cited 39
Lotus / Glycine L. japonicus