A signal sequence mutant defective in export of ribose-binding protein and a corresponding pseudorevertant isolated without imposed selection.

A. Iida, J. M. Groarke, S. Park, J. Thom, J. H. Zabicky, G. L. Hazelbauer, L. L. Randall

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Ribose-binding protein is exported to the periplasmic compartment of Escherichia coli by a process that involves proteolytic cleavage of an amino-terminal extension of amino acids from the precursor form of the protein. In a collection of mutants isolated as defective in the Rbs transport system, a strain was identified that contained only precursor ribose-binding protein, none of which was exported to its normal location in the periplasm. The mutated rbsB contained a base substitution that results in a change of leucine to a proline at position-17 in the signal sequence. A pseudorevertant of the mutant contained proteolytically processed, active ribose-binding protein in the periplasm. The pseudorevertant rbsB carried a second mutation: serine at position-15 in the signal sequence was changed to phenylalanine. Isolation of a signal sequence mutant and a corresponding pseudorevertant without specific selection or site-directed mutagenesis emphasizes the possibility of obtaining export mutants without the use of procedures that could bias or limit the range of mutations found. Explanation of the extreme phenotype of the mutant and the effective correction of that phenotype in the pseudorevertant requires extension of current notions of critical features of signal sequences.

Original languageEnglish
Pages (from-to)1875-1880
Number of pages6
JournalThe EMBO journal
Volume4
Issue number7
DOIs
StatePublished - Jul 1985

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