Different sec‐requirements for signal peptide cleavage and protein translocation in a model E. coli protein

FEBS Letters

Nilsson, IngMarie¹  Gafvelin, Guro¹  von Heijne, Gunnar¹ 

[1] Department of Molecular Biology, Karolinska Institute Center for Structural Biochemistry, NOVUM, S-141 57 Huddinge, Sweden

关键词: Protein secretion;    Protein export;    Signal peptide;   

DOI  :  10.1016/0014-5793(93)81316-R

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We describe a secretory E. coli protein with a novel phenotype: signal peptide cleavage is largely unaffected whereas chain translocation is efficiently blocked under conditions where SecA, a central component of the secretory machinery, is rendered non-functional, and we have traced this phenotype to the presence of a mildly hydrophobic segment located ~30 residues downstream of the signal peptide. When this segment is deleted, normal SecA-dependent signal peptide cleavage and chain translocation is observed; when its hydrophobicity is increased, it becomes a permanent membrane anchor with cleavage of the signal peptide and membrane insertion both being SecA-independent. These findings suggest that the initial insertion of the signal peptide across the membrane can be uncoupled from the translocation process proper.

【 授权许可】

Unknown