OVER-EXPRESSION OF THE YEAST BFR2 GENE PARTIALLY SUPPRESSES THE GROWTH DEFECTS INDUCED BY BREFELDIN-A AND BY 4 ER-TO-GOLGI MUTATIONS

The fungal metabolite Brefeldin A (BFA) disrupts the Golgi apparatus a nd its incoming protein flux. We developed a genetic approach to ident ify yeast proteins involved in the protein transport step that BFA blo cks. The BFR2 gene (YDR299W) was thus isolated as a high-copy suppress or of the growth defects induced by BFA in a sensitive strain of Sacch aromyces cerevisiae. Although BFR2 over-expression did not cause a sec retory block or slow-down, it partially suppressed the growth defect o f four mutants blocked at the step of budding or docking of small vesi cles en route to the Golgi (sec13-1, sec16-2, sec23-1, ypt1-1). The es sential BFR2 gene was predicted to encode an extremely hydrophilic pro duct containing two short regions with potential coiled-coils, one of which corresponds to a cluster of acidic residues.