Isolation and characterisation of a gene encoding verprolin, a novel proline-rich protein in the yeast Saccharomyces cerevisiae.

A gene (VRPl) encoding a novel proline-rich protein (verprolin) has been isolated from the yeast Saccharomyces cerevisiae as a result of its hybridisation to a chick vinculin cDNA probe. The deduced protein sequence contains 24% proline residues present as proline-rich motifs throughout the verprolin sequence. Several of these motifs resemble recently identified sequences shown to bind Src Homology 3 (SH3) domains in vitro. Replacement of the wild-type VRP1 allele with a mutant allele results in strains that grow slower than wild-type strains and are temperature-sensitive. The vrpl mutants are impaired in both cell shape and size and display aberrant chitin and actin localisation. These phenotypic characteristics resemble those observed in yeast cytoskeletal mutants. Using the data generated in this study, together with the rapidly accumulating data on SH3 domains, the cytoskeleton and signal- transduction, it is possible to speculate as to the in vivo role of verprolin.