Analysis of the influence of the N- and C- terminal domains of a signal sequence on SRP dependence AND Investigating the essentiality of genes in the presence of azide

[摘要] Project 1: Proteins destined for export by the Sec pathway in E. coli have cleavable N-terminal signal sequences, consisting of a hydrophobic core flanked by shorter N- and C-terminal domains. Signal sequences are thought to determine the targeting pathway through recognition by SRP or SecA.The hydrophobicity of the core is thought to be the determining factor within the signal sequence for SRP recognition. In this study, the N- or C-terminal portions of an SRP-dependent signal sequence were replaced by those of SecA-dependent signal sequences that have similarly hydrophobic cores.In order to detect the targeting pathway of choice the hybrid signal sequences were fused to the cytoplasmic protein thioredoxin, which can be used as a reporter for cotranslational export.The results suggest a role for the C-terminal region of the signal sequence in SRP dependence. Project 2: Sodium azide is thought to cause toxicity in E. coli by targeting SecA, an essential ATPase that drives protein export.As azide causes translocation stress, it could be used to identify the functions of uncharacterised secretion proteins-particularly ones that become more important during translocation stress. The purpose of this study was to investgate how the cell responds to severe translocation stress, using transposon-directed insertion site sequencing.

[发布机构] University:University of Birmingham;Department:School of Biosciences

[关键词] Q Science;QP Physiology