The finger subdomain of yeast telomerase cooperates with Pif1p to limit telomere elongation.
Telomere synthesis depends on telomerase, which contains an RNA subunit linked to a specialized reverse transcriptase subunit and several associated proteins. Here we report the characterization of four mutations in the yeast reverse transcriptase subunit Est2p that cause an overelongation of telomeres and an increase in the association of Est1p with telomeres during S phase. These 'up-mutations' are clustered in the finger subdomain of the reverse transcriptase. We show that the catalytic properties of the up-mutant telomerases are not improved in vitro. In vivo, the up-mutations neither bypass the activation step governed by Cdc13p nor do they uncouple telomerase from the Rap1p inhibition pathway. In the presence of the up-mutations, however, the ability of the Pif1p helicase to decrease telomere length and to inhibit the association of Est1p with telomeres is impaired. In addition, Pif1p associates in vivo with the telomerase RNA (TLC1) in a way that depends on the finger subdomain. We propose that, in addition to its catalytic role, the finger subdomain of Est2p facilitates the action of Pif1p at telomeres.
Eugster
Anne
A
Laboratoire de Biologie Moléculaire et Cellulaire, UMR5161, IFR128, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
Lanzuolo
Chiara
C
Bonneton
Manon
M
Luciano
Pierre
P
Pollice
Alessandra
A
Pulitzer
John F
JF
Stegberg
Emma
E
Berthiau
Anne-Sophie
AS
Förstemann
Klaus
K
Corda
Yves
Y
Lingner
Joachim
J
Géli
Vincent
V
Gilson
Eric
E
D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D017434:Protein Structure, Tertiary; D012331:RNA, Fungal / Q000378:metabolism; D016196:S Phase / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism*
D004268:DNA-Binding Proteins; D012331:RNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; C099024:EST1 protein, S cerevisiae; D019098:Telomerase; C085463:PIF1 protein, S cerevisiae; D004265:DNA Helicases