Matsuguchi Tet, Blackburn Elizabeth
Department of Biochemistry and Biophysics, University of California , San Francisco, CA , United States.
PeerJ. 2016 Jan 4;4:e1534. doi: 10.7717/peerj.1534. eCollection 2016.
Telomerase core enzyme minimally consists of the telomerase reverse transcriptase domain-containing protein (Est2 in budding yeast S. cerevisiae) and telomerase RNA, which contains the template specifying the telomeric repeat sequence synthesized. Here we report that in vivo, a fraction of S. cerevisiae telomerase RNA (TLC1) molecules form complexes containing at least two molecules of TLC1, via two separable modes: one requiring a sequence in the 3' region of the immature TLC1 precursor and the other requiring Ku and Sir4. Such physical TLC1-TLC1 association peaked in G1 phase and did not require telomere silencing, telomere tethering to the nuclear periphery, telomerase holoenzyme assembly, or detectable Est2-Est2 protein association. These data indicate that TLC1-TLC1 associations reflect processes occurring during telomerase biogenesis; we propose that TLC1-TLC1 associations and subsequent reorganization may be regulatory steps in telomerase enzymatic activation.
端粒酶核心酶最少由含端粒酶逆转录酶结构域的蛋白质（芽殖酵母酿酒酵母中的Est2）和端粒酶RNA组成，端粒酶RNA包含指定合成的端粒重复序列的模板。我们在此报告，在体内，酿酒酵母端粒酶RNA（TLC1）分子的一部分通过两种可分离的模式形成包含至少两个TLC1分子的复合物：一种模式需要未成熟TLC1前体3'区域中的序列，另一种模式需要Ku和Sir4。这种TLC1-TLC1的物理缔合在G1期达到峰值，并且不需要端粒沉默、端粒与核周的连接、端粒酶全酶组装或可检测到的Est2-Est2蛋白质缔合。这些数据表明，TLC1-TLC1缔合反映了端粒酶生物发生过程中发生的过程；我们提出，TLC1-TLC1缔合及随后的重组可能是端粒酶酶促激活的调节步骤。
