title: Proteomics of yeast telomerase identified Cdc48-Npl4-Ufd1 and Ufd4 as regulators of Est1 and telomere length.
abstract: Almost 400 genes affect yeast telomere length, including Est1, which is critical for recruitment and activation of telomerase. Here we use mass spectrometry to identify novel telomerase regulators by their co-purification with the telomerase holoenzyme. In addition to all known subunits, over 100 proteins are telomerase associated, including all three subunits of the essential Cdc48-Npl4-Ufd1 complex as well as three E3 ubiquitin ligases. The Cdc48 complex is evolutionarily conserved and targets ubiquitinated proteins for degradation. Est1 levels are ∼40-fold higher in cells with reduced Cdc48, yet, paradoxically, telomeres are shorter. Furthermore, Est1 is ubiquitinated and its cell cycle-regulated abundance is lost in Cdc48-deficient cells. Deletion of the telomerase-associated E3 ligase, Ufd4, in cdc48-3 cells further increases Est1 abundance but suppresses the telomere length phenotype of the single mutant. These data argue that, in concert with Ufd4, the Cdc48 complex regulates telomerase by controlling the level and activity of Est1.
authors.affiliation: Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Washington Road, 08544 Princeton, New Jersey, USA.
authors.forename: Kah-Wai
authors.initials: KW
authors.lastname: Lin
authors.affiliation: Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Washington Road, 08544 Princeton, New Jersey, USA.
authors.forename: Karin R
authors.initials: KR
authors.lastname: McDonald
authors.affiliation: Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Washington Road, 08544 Princeton, New Jersey, USA.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Guise
authors.affiliation: Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Washington Road, 08544 Princeton, New Jersey, USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Chan
authors.affiliation: Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Washington Road, 08544 Princeton, New Jersey, USA.
authors.forename: Ileana M
authors.initials: IM
authors.lastname: Cristea
authors.affiliation: Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Washington Road, 08544 Princeton, New Jersey, USA.
authors.forename: Virginia A
authors.initials: VA
authors.lastname: Zakian
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D015139:Blotting, Southern; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000378:metabolism*; D013058:Mass Spectrometry; D029543:Nucleocytoplasmic Transport Proteins / Q000378:metabolism*; D040901:Proteomics; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D019098:Telomerase / Q000378:metabolism*; D059505:Telomere Homeostasis; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D000074405:Valosin Containing Protein; D033921:Vesicular Transport Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; C104361:NPL4 protein, S cerevisiae; D029543:Nucleocytoplasmic Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; C444652:UFD1 protein, S cerevisiae; D033921:Vesicular Transport Proteins; C509339:Ufd4 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; C099024:EST1 protein, S cerevisiae; D019098:Telomerase; D000251:Adenosine Triphosphatases; C000614177:CDC48 protein, S cerevisiae; D000074405:Valosin Containing Protein