化脓链球菌中野生型和突变体FtsB蛋白的铁色素结合特性

Ferrichrome Binding Characteristics of Wild Type-and Mutant FtsBs in Streptococcus pyogenes

目的:进一步比较化脓链球菌中野生型和Y137A、W204A突变型FtsB蛋白的铁色素结合特性,确定铁色素结合位点。方法:制备野生型和Y137A、W204A突变型FtsB蛋白,采用ICP-MS和ITC比较其铁色素结合能力;Na2SO4还原实验比较铁色素的还原速率;CD热变性和盐酸胍化学变性实验比较其铁色素结合稳定性。结果:Y137A、W204A突变型FtsB蛋白的铁色素结合能力和结合稳定性均低于野生型蛋白,铁色素的还原速率均高于野生型蛋白,可见Tyr137和Trp204是FtsB蛋白重要的铁色素结合位点。结论:进一步确定了Tyr137和Trp204氨基酸残基在FtsB与铁色素结合中的重要作用,为深入研究细菌中的铁色素转运机理及开发疫苗候选物奠定了一定的理论基础。

Objective： To further compare the ferrichrome binding characteristics mutant Y137A, W204A in Streptococcus pyogenes, and to further determine the Methods： Wild type FtsB and Y137A, W204A mutant proteins were prepared between wild type FtsB and ferrichrome binding sites. Their ferrichrome binding capacities were compared by ICP-MS and ITC; Their ferrichrome reduction rates were measured by UV-vis spectrometer using Na2 S： 04 as the reductive agent; Their ferrichrome binding stabilities were analyzed via thermal and GuHC1 denaturation. Results： The binding affinity and stability of the mutants Y137A and W204A with ferrichrome were both lower than that of wild-type FtsB. Whereas their ferrichrome reduction rates were higher than wild-type FtsB. Thus the residues Try137 and Trp204 play an important role in ferrichrome binding of FtsB. Conclutions： A valuable information for the understanding of ferrichrome transport in bacteria was provided, which may be helpful for the development of novel strategies in the control of bacterial infection.