IDENTIFICATION AND ANALYSIS OF HOMOLOGS OF SACCHAROMYCES-CEREVISIAE SPT3 SUGGEST CONSERVED FUNCTIONAL DOMAINS

Spt3 of Saccharomyces cerevisiae is a factor required for normal trans cription from particular RNA polymerase II-dependent promoters. As a s tep towards analysing Spt3 structure-function relationships, we have i dentified and studied Spt3 homologues from three other yeasts: Kluyver omyces lactis, Clavispora opuntiae and Schizosaccharomyces pombe. Alig nment of their predicted amino acid sequences shows an overall identit y of 30% between all four homologues and suggests that three conserved domains are present in Spt3. When tested for function in S. cerevisia e, K. lactis SPT3 was shown to fully complement and S. pombe SPT3 to p artially complement an spt3 Delta mutation. These data demonstrate tha t Spt3 is functionally conserved among distantly related yeasts. The n ew sequences have been entered in GenBank: AF005930 (K. lactis SPT3), AF005932 (C. opuntiae SPT3) and AF005931 (S. pombe SPT3). (C) 1998 Joh n Wiley & Sons, Ltd.