Characterization And Functional Study Of RNA Binding Proteins In Serratia Plymuthica

Serratia plymuthica G3 was isolated from the stems of wheat (Triticum aestivum L.).It is capable to produce several antifungal factors, such as chitinases,proteases,and the antibiotic pyrrolnitrin and showed antifungal activity against several pathogens in the dual-culture test on plates.Hfq and RsmA,two conservative RNA-binding proteins in bacterium,are involved in global regulation of the expression of bacterium genes at post-transcriptional level to modulate bacterial various physiological processes and coordinate adaptation to the changing environment.In this sduty,using S.plymuthica G3 as the model organism,we preliminary investigated the functions of RNA-binding proteins Hfq and RsmA by gene cloning,overexpressio,gene mutagenesis and complementary analysis.The major results achieved are as follows:(1) Molecular coloning and sequencing the coding genes of the two RNA-binding proteins Hfq and RsmA;as well as bioinformatics and phylogenetic analyses.(2) We constructed G3/hfq+ and G3/rsmA+ overexpression strain, and verified by Western blot,as well as constructed hfq gene deletion and insertion mutant,complementary strain and control strain.(3) Mutational analysis showed that Hfq positively regulates several biocontrol phenotypes of S.plymuthica G3,such as protease,chitinase、antifungal activity,motility and bilfilm formation.The exoenzymes and antifungal activity of hfq mutant decrease obviously compared with the wide type strain G3.Its motility and biofilm formation also has a certain extent decreation.Almost these biocontrol-related phenotypes had partially or fully restored to the wild type level in complementary strain.(4) Overexpession of RsmA in G3 demonstrated that RsmA control the biocontrol phenotypes negatively in global regulation.The protease and chitinase activity of the mutant decread obiously compared with G3.The motility and biofilm formation are repressed too.The vector control strain had the same phenotypes with the wide type.The all results above suggest that the RNA-binding Hfq is closed related to the biocontrol ability of S.plymuthica G3,show potential application as genetic manipulation target.Hfq can be used to improved biocontrol efficacy and stability,provide new strategy to improve biocontrol bacterium inoculum.