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Papers In Press, published online ahead of print May 19, 2006
School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599-7360
Corresponding Author: jarstfer{at}unc.edu
Telomerase is a ribonucleoprotein complex that synthesizes the G-rich DNA found at the 3’ ends of linear chromosomes. Human telomerase consists minimally of a catalytic protein (hTERT) and a template-containing RNA (hTR), though other proteins are involved in regulating telomerase activity in vivo. Several chaperone proteins including hsp90 and p23 have demonstrable roles in establishing telomerase activity both in vitro and in vivo, and previous reports indicate that hsp90 and p23 are required for the reconstitution of telomerase activity from recombinant hTERT and hTR. Here we report that hTERT and hTR associate in the absence of a functional hsp90-p23 heterocomplex. We also report that hsp90 inhibitors geldanamycin and novobiocin inhibit recombinant telomerase even after telomerase is assembled. Inhibition by geldanamycin could be overcome by allowing telomerase to first bind its primer, suggesting a role for hsp90 in loading telomerase onto the telomere. Inhibition by novobiocin could not similarly be overcome but instead resulted in destabilization of the hTERT polypeptide. We propose that the hsp90-p23 complex fine-tunes and stabilizes a functional telomerase structure allowing primer loading and extension.
J. Biol. Chem, 10.1074/jbc.M511067200
Submitted on October 11, 2005
Revised on May 19, 2006
Accepted on May 19, 2006
The biochemical role of the heat shock protein 90 chaperone complex in establishing human telomerase activity
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