A conservative amino acid substitution, arginine for lysine, abolishes export of a hybrid protein in Escherichia coli. Implications for the mechanism of protein secretion

A hybrid protein that comprises the beta-lactamase signal peptide fused precisely to chicken muscle triosephosphate isomerase is not secreted into the periplasm of Escherichia coli. The protein can be secreted, however, if an arginine residue at position 3 of the isomerase is replaced by either a se...

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Bibliographic Details
Published in:The Journal of biological chemistry 1989-11, Vol.264 (33), p.20082-20088
Main Authors: SUMMERS, R. G, HARRIS, C. R, KNOWLES, J. R
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Arginine
beta -lactamase
beta-Lactamases - biosynthesis
beta-Lactamases - genetics
Biological and medical sciences
Carbohydrate Epimerases - genetics
Chickens
Escherichia coli - enzymology
Escherichia coli - genetics
Fundamental and applied biological sciences. Psychology
Genic rearrangement. Recombination. Transposable element
Lysine
Molecular and cellular biology
Molecular genetics
Molecular Sequence Data
Muscles - enzymology
Mutation
Plasmids
Protein Conformation
Protein Sorting Signals - biosynthesis
Protein Sorting Signals - genetics
Recombinant Fusion Proteins - biosynthesis
triose-phosphate isomerase
Triose-Phosphate Isomerase - biosynthesis
Triose-Phosphate Isomerase - genetics
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Summary:A hybrid protein that comprises the beta-lactamase signal peptide fused precisely to chicken muscle triosephosphate isomerase is not secreted into the periplasm of Escherichia coli. The protein can be secreted, however, if an arginine residue at position 3 of the isomerase is replaced by either a serine or a proline residue. In contrast, replacement of a neighboring lysine residue has no effect on secretion of the protein. Furthermore, if the arginine is removed from position 3 to generate a secreted protein, but is then reintroduced in place of the neighboring lysine, the blockade to secretion is re-established. The singular effect of the arginine residue on secretion does not result from the role this residue plays in the formation or stabilization of the native isomerase structure: mutational alterations remote from the N terminus of the isomerase that prevent the proper folding of the protein do not relieve the block to secretion. The finding that an arginine residue prevents secretion while a lysine residue does not, suggests that basic residues near the mature N terminus of a secreted protein must be deprotonated if orderly export is to occur. This implies that the signal peptide along with the N-terminal portion of the mature protein partitions directly into the lipid bilayer in the course of the secretory process.
ISSN:0021-9258
1083-351X