Identification and characterization of PilZ domain-containing proteins in pathogenic-ity and motility of Pseudomonas syringae pv.actinidiae
PilZ domain-containing proteins are the largest known receptors of second messenger c-di-GMP in bacteria,but the functions and underlying mechanisms have not been reported in Pseudomonas syringae pv.ac-tinidiae(Psa).To reveal the contribution and regulation mechanism of PilZ domain-containing proteins to the pathogenicity of Psa and to provide new ideas for controlling kiwifruit bacterial canker.Firstly,genome analysis and sequence alignment of Psa M228 were performed to identify the PilZ domain-containing proteins of Psa and analyze the conserved c-di-GMP binding motif.Then,homologous recombination was used to construct deletion mutants,and the pathogenicity,motility and growth between mutants and wild type were determined by leaf discs vacuum infiltration,soft agar plate assays and growth curve measurment,respectively.The transcripts of pathogenicity-and motility-relative genes in WT and △Psa_2195 mutant were measured by qRT-PCR.The results show that there are eight PilZ domain-containing proteins in Psa M228,among them PSA_2195 and PSA_1975 have neither a conserved RxxxR motif nor a(D/N)xSxxG binding motif that binds to c-di-GMP.The pathoge-nicity of △Psa_1116,△Psa_2195,△Psa_2203,△Psa_762,△Psa_4490 and △Psa_4763 were significantly reduced.Deletion of PSA_1116 and PSA_2195,PSA_3989,PSA_762 affected swimming motility and swarming motility,respectively.The growth curve of all mutants are no significant difference with wild type M228.Among all PilZ domain proteins,PSA_2195 regulates the transcription of flagella genes fllgA,filE and T3SS genes.Tak-ing together,our research revealed the function of eight PilZ domain-containing proteins in regulating pathoge-nicity and motility of Psa and the simple molecular mechanisms of PSA_2195.
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