External Loops at the C Terminus of Erwinia chrysanthemi Pectate Lyase C Are Required for Species-Specific Secretion through the Out Type II Pathway

摘要: The type II secretion system (main terminal branch of the general pathway) is used by diverse gram-negative bacteria to secrete extracellular proteins. Proteins secreted this pathway are synthesized with an N-terminal signal peptide which removed upon translocation across inner membrane, but signals target mature proteins for outer membrane unknown. plant pathogens Erwinia chrysanthemi and carotovora several isozymes pectate lyase (Pel) out -encoded pathway. However, these two cannot Pels encoded heterologously expressed pel genes from other species, suggesting existence species-specific within functional cluster E. carried on cosmid pCPP2006 enables Escherichia coli , not Pels. We exploited high sequence similarity between PelC Pel1 construct 15 hybrid in different regions were replaced homologous sequences Pel1. differential (pCPP2006) revealed M118 D175 V215 C329 as required PelC. propose that primary targeting contained external loops formed G274 dependent residues D170 proper positioning.