Telomerase repeat addition processivity is increased at critically short telomeres in a Tel1-dependent manner in Saccharomyces cerevisiae.
Telomerase is the ribonucleoprotein enzyme that elongates telomeres to counteract telomere shortening. The core enzyme consists of a reverse transcriptase protein subunit and an RNA subunit. The RNA subunit contains a short region that is used as a template by the reverse transcriptase to add short, tandem, G-rich repeats to the 3' ends of telomeres. By coexpressing two RNA subunits that differ in the telomeric repeat sequence specified and examining the telomere extensions after one cell cycle, we determined that Saccharomyces cerevisiae telomerase can dissociate and reassociate from a given telomere during one cell cycle. We also confirmed that telomerase is nonprocessive in terms of telomeric repeat addition. However, repeat addition processivity is significantly increased at extremely short telomeres, a process that is dependent on the ATM-ortholog Tel1. We propose that this enhancement of telomerase processivity at short telomeres serves to rapidly elongate critically short telomeres.
Chang
Michael
M
Swiss Institute for Experimental Cancer Research (ISREC), CH-1066 Epalinges, Switzerland.
Arneric
Milica
M
Lingner
Joachim
J
D001483:Base Sequence; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D020080:Tandem Repeat Sequences; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism*; D013698:Templates, Genetic
D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases; C513623:TEL1 protein, S cerevisiae; D019098:Telomerase