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Signal peptide cleavage regions. Functional limits on length and topological implications
R G Jain1, S L Rusch, D A Kendall
1Department of Molecular & Cell Biology, University of Connecticut, Storrs 06269.
The Journal of Biological Chemistry
|June 10, 1994
Summary
The length of the signal peptide cleavage region is critical for efficient protein export. Optimal lengths between 3 and 9 residues ensure proper signal peptidase processing and protein translocation.
Area of Science:
- Molecular Biology
- Protein Biochemistry
- Cellular Biology
Background:
- Signal peptides direct proteins to the cell membrane for export.
- Signal peptidase cleaves signal peptides, a crucial step in protein secretion.
- Understanding signal peptide topology is key to protein export mechanisms.
Purpose of the Study:
- To investigate the relationship between signal peptide cleavage region length and signal peptidase activity.
- To determine the optimal length constraints for signal peptide processing.
- To elucidate the topological constraints of signal peptide-membrane interactions.
Main Methods:
- Construction of signal peptide cleavage region mutants using polymers of alanine and glutamine residues.
- Systematic variation of cleavage region length from 3 to 13 residues.
- Analysis of mutant processing efficiency using Escherichia coli alkaline phosphatase signal peptide.
Main Results:
- Cleavage regions of 3 to 9 residues were efficiently processed by signal peptidase.
- Processing efficiency significantly decreased for lengths greater than 9 residues.
- No processing was observed for a 13-residue cleavage region, indicating length-dependent constraints.
Conclusions:
- Signal peptidase recognition and cleavage are highly sensitive to the length of the cleavage region.
- The signal peptidase active site likely interacts with the periplasmic side of the inner membrane.
- Cleavage region length constraints suggest dependence on broader signal peptide-membrane interactions.