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Int. J. Mol. Sci. 2011, 12(5), 2901-2916; doi:10.3390/ijms12052901
Article

Dissimilar Roles of the Four Conserved Acidic Residues in the Thermal Stability of Poly(A)-Specific Ribonuclease

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Received: 27 January 2011; in revised form: 23 March 2011 / Accepted: 18 April 2011 / Published: 3 May 2011
(This article belongs to the Section Biochemistry, Molecular Biology and Biophysics)
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Abstract: Divalent metal ions are essential for the efficient catalysis and structural stability of many nucleotidyl-transfer enzymes. Poly(A)-specific ribonuclease (PARN) belongs to the DEDD superfamily of 3'-exonucleases, and the active site of PARN contains four conserved acidic amino acid residues that coordinate two Mg2+ ions. In this research, we studied the roles of these four acidic residues in PARN thermal stability by mutational analysis. It was found that Mg2+ significantly decreased the rate but increased the aggregate size of the 54 kDa wild-type PARN in a concentration-dependent manner. All of the four mutants decreased PARN thermal aggregation, while the aggregation kinetics of the mutants exhibited dissimilar Mg2+-dependent behavior. A comparison of the kinetic parameters indicated that Asp28 was the most crucial one to the binding of the two Mg2+ ions, while metal B might be more important in PARN structural stability. The spectroscopic and aggregation results also suggested that the alterations in the active site structure by metal binding or mutations might lead to a global conformational change of the PARN molecule.
Keywords: aggregation kinetics; magnesium ions; poly(A)-specific ribonuclease (PARN); structural stability; thermal aggregation; two-metal-ion catalysis aggregation kinetics; magnesium ions; poly(A)-specific ribonuclease (PARN); structural stability; thermal aggregation; two-metal-ion catalysis
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

He, G.-J.; Liu, W.-F.; Yan, Y.-B. Dissimilar Roles of the Four Conserved Acidic Residues in the Thermal Stability of Poly(A)-Specific Ribonuclease. Int. J. Mol. Sci. 2011, 12, 2901-2916.

AMA Style

He G-J, Liu W-F, Yan Y-B. Dissimilar Roles of the Four Conserved Acidic Residues in the Thermal Stability of Poly(A)-Specific Ribonuclease. International Journal of Molecular Sciences. 2011; 12(5):2901-2916.

Chicago/Turabian Style

He, Guang-Jun; Liu, Wei-Feng; Yan, Yong-Bin. 2011. "Dissimilar Roles of the Four Conserved Acidic Residues in the Thermal Stability of Poly(A)-Specific Ribonuclease." Int. J. Mol. Sci. 12, no. 5: 2901-2916.



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