ANALYSIS OF COPPER-INDUCED METALLOTHIONEIN EXPRESSION USING AUTONOMOUSLY REPLICATING PLASMIDS IN CANDIDA-GLABRATA

Candida glabrata strains and a stable plasmid were developed that were suitable for analysis of copper-inducible expression from promoters o f the three metallothionein (MT) genes. The two homologous MTII genes, MTIIa and MTIIb, encode the same polypeptide but are differentially i nduced by copper salts. MTIIb is more highly inducible than MTIIa and cells harboring a single MTIIb exhibit a greater resistance to copper salts compared to cells harboring a single MTIIa. The differential cop per inducibility was mapped to sequences between -503 and -292 upstrea m of the MT coding sequences. Expression of MTI is highly Cu-regulated , but this MT gene confers much less resistance than MTII genes.