BRO1, A NOVEL GENE THAT INTERACTS WITH COMPONENTS OF THE PKC1P-MITOGEN-ACTIVATED PROTEIN-KINASE PATHWAY IN SACCHAROMYCES-CEREVISIAE

Yeast cells with mutations in BRO1 display phenotypes similar to those caused by deletion of BCK1, a gene encoding a MEK kinase that functio ns in a mitogen-activated protein kinase pathway mediating maintenance of cell integrity. bro1 cells exhibit a temperature-sensitive growth defect that is suppressed by the addition of osmotic stabilizers or Ca 2+ to the growth medium or by additional copies of the BCK1 gene, At p ermissive temperatures, bro1 mutants are sensitive to caffeine and res pond abnormally to nutrient limitation, A null mutation in BRO1 is syn thetically lethal with null mutations in BCK1, MPK1, which encodes a m itogen-activated protein kinase that functions downstream of Bck1p, or PKC1, a gene encoding a protein kinase C homolog that activates Bck1p . Analysis of the isolated BRO1 gene revealed that it encodes a novel, 97-kDa polypeptide which contains a putative SH3 domain-binding motif and is homologous to a protein of unknown function in Caenorhabditis elegans.