Characterisation of preYvaY export reveals differences in the substrate specificities of Bacillus subtilis and Escherichia coli leader peptidases.

摘要: Translocation, processing and secretion of YvaY, a Bacillus subtilis protein unknown function, were characterised both in B. Escherichia coli. In its natural host subtilis, YvaY was transiently synthesised at the end exponential growth phase. It efficiently secreted into culture supernatant spite calculated membrane spanning domain mature part protein. E. coli, despite high conservation Sec-dependent transport components, preYvaY strongly impaired. To uncover which elements coli translocation systems are responsible for observed substrate specificity, components Sec-system co-expressed besides yvaY Expression secA or secYEG genes did not affect processing, but expression signal peptidase significantly enhanced While major peptidases SipS SipT had strong stimulatory effect on minor SipU, SipV SipW far less These results reveal that targeting is mediated by Sec proteins performed LepB. Thus, differences specificities LepB Sip provide bottleneck export Significant slower absence SecB indicated mediates precursor.