The Study On The Regulation Of Growth And Development By The Conservative Regulator MtrA In Streptomyces Venezuela

MtrA is an important and conservative regulator in actinomycetes.In Mycobacterium tuberculosis and Corynebacterium glutamate,MtrA is an essential regulator for bacteria's survival.In Mycobacterium tuberculosis,MtrAMTB regulates cell proliferation by interacting with oriC.In Corynebacterium glutamate,MtrACGL is important in maintaining cell morphology,resistance to antibiotics and osmotic protection.Target genes of MtrAcGL have a variety of functions,including encoding presumed cell wall peptidases,transporters,and membrane proteins.In this paper,the function of MtrA in Streptomyces Venezuela was preliminarily studied.The purpose of this study was to explore the role of MtrA in the life cycle of Streptomyces Venezuela and its regulation on the aerial hyphae of Streptomyces.This experiment first builds knock-out plasmid containing target gene's upstream and downstream homology arms,and then the gene was transferred by intergeneric conjugation.By phenotypic analysis and growth curve drawing,I observed that mutant strain A2756's growth is significantly slow,the productions of aerial hyphae and spores in mutant strain are blocked.In order to further confirm that the phenotypic change of mutant strain A2756 is due to the absence of sven2756,the study use integrated vector pMS82,which contain sven2756 complete coding sequence and promoter regions,and get the complemented strain.Phenotypic analysis and growth curve observed that aerial hyphae and spores,production of complemented strain is similar to the wild type strain ISP5230.Thus it can be concluded that the phenotypic change of mutant strain is caused by the absence of sven2756.The strains were enriched and the expression of some genes in ISP5230 and?2756 was quantitatively analyzed by realtime-PCR.The results showed that there were significant differences in the expression of bldD,bldH,bldN,bldG,bldC,bldM,which controlling the production of Streptomyces aerial hyphae formation.To further determine that SVEN2756 is involved in the regulation of growth and aerial hyphae formation,we expressed and purified His-SVEN2756 protein.Through EMSAs,it was found that SVEN2756 had direct interaction with the promoter of bldD,but no interaction with the promoters of bldH,bldN,bldG,bldC,bldM.Based on the above experimental results,it was found that MtrA,a conservation regulatory factor in actinomycetes,may be involved in the regulation of growth and development,aerial hyphae formation and spore production,but the specific regulatory mechanism is not clear.