tailieunhanh - Báo cáo khoa học: Conformational stability and multistate unfolding of poly(A)-specific ribonuclease

Poly(A)-specific ribonuclease (PARN) specifically catalyzes the degradation of the poly(A) tails of single-stranded mRNAs in a highly processive mode. PARN participates in diverse and important intracellular processes by act-ing as a regulator of mRNA stability and translational efficiency. In this article, the equilibrium unfolding of PARN was studied using both guani-dine hydrochloride and urea as chemical denaturants. | ỊFEBS Journal Conformational stability and multistate unfolding of poly A -specific ribonuclease Guang-Jun He Ao Zhang f Wei-Feng Liu Yuan ChengỊ and Yong-Bin Yan State Key Laboratory of Biomembrane and Membrane Biotechnology Department of BiologicalSciences and Biotechnology Tsinghua University Beijing China Keywords chemical denaturants equilibrium unfolding intermediate poly A -specific ribonuclease PARN quaternary structure structural stability Correspondence . Yan Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China Fax 86 10 6277 1597 Tel 86 10 6278 3477 E-mail ybyan@ These authors contributed equally to this work Present address fLerner Research Institute Cleveland Clinic OH USA ỊDepartment of Biochemistry and Biophysics Schoolof Medicine University of North Carolina at Chapel Hill NC USA Received 4 October 2008 revised 23 February 2009 accepted 17 March 2009 doi Poly A -specific ribonuclease PARN specifically catalyzes the degradation of the poly A tails of single-stranded mRNAs in a highly processive mode. PARN participates in diverse and important intracellular processes by acting as a regulator of mRNA stability and translational efficiency. In this article the equilibrium unfolding of PARN was studied using both guanidine hydrochloride and urea as chemical denaturants. The unfolding of PARN was characterized as a multistate process but involving dissimilar equilibrium intermediates when denatured by the two denaturants. A comparison of the spectral characteristics of these intermediates indicated that the conformational changes at low concentrations of the chemical denaturants were more likely to be rearrangements of the tertiary and quaternary structures. In particular an inactive molten globule-like intermediate was identified to exist as soluble non-native oligomers and the formation of the oligomers was modulated by electrostatic interactions. An active .