Functional Analysis Of Copper Resistance Related Gene CusB In Acidovorax Citrulli

Acidovorax citrulli have infected on plants of the family cucurbitaceae,it will result in a devastating melon bacterial fruit blotch(BFB), the disease has spread rapidly around the world, it causing serious economic losses to the local melon industries. From now on, copper bactericide is still an dominating for bacterial fruit blotch of melons,but the microorganism is well-adapted and mutable, the resistance of bacterium has enhanced with the copper being widely used. Thereby, the research of A.c copper resistant mechanism is particularly crucial.We made a lot of analysis on the cusB gene of RND family efflux pumps of bioinformatics software, then we use of cusB gene deletion mutant strains prepared of laboratory. The gene’s function was analyzed by comparing the difference between the wild and mutant and functional complementation strain in basic phaenotype tests. The main conclusions are as follows:First, bioinformatics analysis of cusB gene in Acidovorax citrulli.The gene cusB is 1185 bp and that protein CusB which has 394 amino acid residues in Acidovorax citrulli genome coding. CusB protein in A.c is more similar to that in Escherichia coli, one part in CusB protein of A.c is found hydrophobic and CusB protein has one transmembrane domain. And it has a number of phosphorylation sites, and subcellular localization at the periplasmic space, CusB protein secondary structure have a plenty of α-helix and coil, β-sheet relatively few.Second, phenotype tests on cusB gene mutant and its complementary strain.The mutant strain is sensitive of copper than wild type FC440. We can draw a conclusion that cusB gene is associated with resistance of copper. The formation of EPS and biofilm of mutant weakened on melon. But the disruption of cusB did not impair its three virulence-associated function, including the pathogenicity and HR, production of extracellular cellulose, proteinase.