[Molecular identification and functional analysis of Clpxoo, a homologue to the nucleotide receptor protein in Xanthomonas oryzae pv. oryzae].
OBJECTIVE
To better understand the mechanisms of cyclic di-GMP signaling in Xanthomonas oryzae pv. oryzae (Xoo),the casual pathogen of bacterial blight of rice, molecular identification of Clpxoo.


METHODS
A putative signal receptor protein was performed through gene cloning, sequencing and deletion analysis.


RESULTS
Sequence analysis showed Clpxoo was a homologue of Crp and Vfr, the cAMP receptor proteins in Escherichia coli and Pseudomonas aeruginosa respectively, which had the cNMP-binding domains (CAP_ED) at N terminal and the DNA-binding domains (HTH_CRP) at C terminal and is highly conserved in the plant-pathogenic Xanthomonas spp. We constructed delta clpxoo through a double crossover recombination and validated by PCR assay, delta clpxoo displayed the reduced motility and extracellular polysaccharide (EPS) production, and increased sensitive to H2O2 toxicity compared with PXO99(A). All these phenotype changes could be partly restored through complementation of mutants by introducing clpxoo. Moreover, we observed no significant changes in production of extracellular cellulase and xylanase in vitro, biofilm formation and induction of hypersensitive response (HR) on non-host tobacco in delta clpxoo compared to PXO99(A).


CONCLUSIONS
Therefore, Clpxoo played a role as one of the global regulator in regulation of flagellar motility, EPS production and H2O2 resistance.
Guan
Wenjing
W
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China. gwj1022@yahoo.com.cn
Wu
Maosen
M
He
Chenyang
C
D000595:Amino Acid Sequence; D003625:Data Collection; D005798:Genes, Bacterial; D006861:Hydrogen Peroxide / Q000633:toxicity*; D008969:Molecular Sequence Data; D009154:Mutation; D012275:Oryza / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology; D017386:Sequence Homology, Amino Acid; D037521:Virulence Factors; D014974:Xanthomonas / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity
D037521:Virulence Factors; D006861:Hydrogen Peroxide