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N‐tail translocation of mature β‐lactamase across the Escherichia coli cytoplasmic membrane
Author(s) -
Mitsopoulos Costas,
Hashemzadeh-Bonehi Lida,
Broome-Smith Jenny K
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)01413-0
Subject(s) - glycophorin , signal peptide , escherichia coli , cytoplasm , chromosomal translocation , biochemistry , proteolysis , biology , membrane protein , bacterial outer membrane , signal peptidase , membrane , peptide , peptide sequence , chemistry , enzyme , gene
Mature β‐lactamase was attached to the N‐terminus of human glycophorin C, an N‐out membrane protein lacking a cleavable signal peptide (an N‐tail membrane protein). When synthesised in Escherichia coli more than 30% of the intact mature β‐lactamase‐glycophorin C molecules assembled N‐out, C‐in into the cytoplasmic membrane. The N‐tail translocated β‐lactamase folded into an enzymatically active form, but it was more susceptible to proteolysis than the equivalent portion of β‐lactamase‐glycophorin C synthesised with an N‐terminal signal peptide. Its translocation was virtually abolished when the N‐out domain of glycophorin C was truncated or when the basic residues C‐terminally flanking the glycophorin C membrane‐spanning segment were replaced with neutral ones.