Human telomerase model shows the role of the TEN domain in advancing the double helix for the next polymerization step

Abstract

Telomerases constitute a group of specialized ribonucleoprotein enzymes that remediate chromosomal shrinkage resulting from the "end-replication" problem. Defects in telomere length regulation are associated with several diseases as well as with aging and cancer. Despite significant progress in understanding the roles of telomerase, the complete structure of the human telomerase enzyme bound to telomeric DNA remains elusive, with the detailed molecular mechanism of telomere elongation still unknown. By application of computational methods for distant homology detection, comparative modeling, and molecular docking, guided by available experimental data, we have generated a threedimensional structural model of a partial telomerase elongation complex composed of three essential protein domains bound to a single-stranded telomeric DNA sequence in the form of a heteroduplex with the template region of the human RNA subunit, TER. This model provides a structural mechanism for the processivity of telomerase and offers new insights into elongation. We conclude that the RNA∶DNA heteroduplex is constrained by the telomerase TEN domain through repeated extension cycles and that the TEN domain controls the process by moving the template ahead one base at a time by translation and rotation of the double helix. The RNA region directly following the template can bind complementarily to the newly synthesized telomeric DNA, while the template itself is reused in the telomerase active site during the next reaction cycle. This first structural model of the human telomerase enzyme provides many details of the molecular mechanism of telomerase and immediately provides an important target for rational drug design.polymerase | protein motions | structure prediction

Structural Analysis Reveals the Deleterious Effects of Telomerase Mutations in Bone Marrow Failure Syndromes

“…Three reported disease mutations (V1025F, N1028H, and V1090M) are located within this pocket of hThumb. We discussed some of these mutations previously in the context of the telomerase model published in PNAS (6,30). With the hThumb structure at hand, we want to point out that these mutations indeed form part of the FVYL pocket of TERT (Fig.…”

Novel myricetin derivatives: Design, synthesis and anticancer activity

“…Chemical shifts are To a solution of 2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-3-(3,4,5-trihydroxy-6-methyl-tetra-hydro-2H-pyran-2-yloxy)-4H-chromen-4-one (5 mmol) in DMF (20 mL) was added K 2 CO 3 (16 mmol), After the mixture was stirred at 25 C for 10 min, methyl iodide (32 mmol) was slowly added, the resulting solution was allowed to 25 C and stirred for 48 h, filtrated, washed with ethyl ether, the filter liquor was then added into the water (100 mL), extracted with ethyl acetate three times, combined organic phase, 2.33 ± 0.14 BIBR1532 b 0.17 ± 0.07 a Telomerase supercoiling activity. b Ethidium bromide and BIBR1532 are reported as a control [19]. The inhibition constant of ethidium toward telomerase has been reported previously.…”

“…In this study, a three-dimension human telomerase model [19] and in silico Schr€ odinger's IFD (Induced Fit Docking) were used to model the binding poses of our designed compounds with hTERT. Before doing the IFD, the structural errors of the model was first corrected manually and then the complex was treated by Protein Prepared Wizard of Schr€ odinger.…”

“…Steczkiewicz et al [19] have constructed a three-dimension human telomerase model by systematically utilizing computational methods for distant homology detection, comparative modeling and molecular docking. In this study, above three-dimension human telomerase model and an advanced docking method e IFD (Induced Fit Docking) of Schr€ odinger were employed to explore the binding mode of BIBR1532, a potent hTERT inhibitor.…”

Elastic network normal modes provide a basis for protein structure refinement

“…These studies by us and others provide important evidence that structures, even when coarse-grained, have an intrinsic tendency to fluctuate in limited numbers of directions. [22][23][24][25][26][27][28][29] The present work to refine predicted protein structures is built upon this foundation.…”