COMPLETION OF THE SACCHAROMYCES-CEREVISIAE GENOME SEQUENCE ALLOWS IDENTIFICATION OF KTR5, KTR6 AND KTR7 AND DEFINITION OF THE 9-MEMBERED KRE2 MNT1 MANNOSYLTRANSFERASE GENE FAMILY IN THIS ORGANISM/

The KRE2/MNT1 mannosyltransferase gene family of Saccharomyces cerevis iae currently consists of the KRE2, YUR1, KTR1, KTR2, KTR3 and KTR4 ge nes. All six encode putative type II membrane proteins with a short cy toplasmic N-terminus, a membrane-spanning region and a highly conserve d catalytic lumenal domain. Here we report the identification of the t hree remaining members of this family in the yeast genome. KTR5 corres ponds to an open reading frame (ORF) of the left arm of chromosome XIV , and KTR6 and KTR7 to ORFs on the left arms of chromosomes XVI and IX respectively. The KTR5, KTR6 and KTR7 gene products are highly simila r to the Kre2p/Mnt1p family members. Initial functional characterizati on revealed that some mutant yeast strains containing null copies of t hese genes displayed cell wall phenotypes. None was K1 killer toxin re sistant but ktr6 and ktr7 null mutants were found to be hypersensitive and resistant, respectively, to the drug Calcofluor White. The sequen ces have been deposited in the GenBank data library under Accession Nu mbers Z71305; U39205; Z46728. (C) 1997 by John Wiley & Sons, Ltd.