Consequences of Mutations that Alter Telomeres in the Yeast K. lactis

Abstract

Telomeres are the structures that comprise the functional ends of eukaryotic chromosomes (For recent reviews, see Blackburn, 1994; Zakian, 1995). In the great majority of eukaryotes, including vertebrates and yeasts, telomeric DNA is composed of tandem arrays of a short repeated sequence. Because the ends of linear DNA molecules cannot be fully replicated by standard DNA polymerases, a specialized means of maintaining chromosome ends is required. In a variety of organisms, these telomeric repeat arrays are known to be maintained by telomerase, a ribonucleoprotein reverse transcriptase that synthesizes single strand copies of the unit telomeric repeat onto the 3’ end of the chromosomal terminus by using part of its RNA subunit as a template (Blackburn, 1994; Zakian, 1995).