TY - JOUR T1 - Kinetic mechanism of human mitochondrial RNase P JF - bioRxiv DO - 10.1101/666792 SP - 666792 AU - Xin Liu AU - Nancy Wu AU - Aranganathan Shanmuganathan AU - Bradley P. Klemm AU - Michael J. Howard AU - Wan Hsin Lim AU - Markos Koutmos AU - Carol A. Fierke Y1 - 2019/01/01 UR - http://biorxiv.org/content/early/2019/06/11/666792.abstract N2 - A first step in processing mitochondrial precursor tRNA (pre-tRNA) is cleavage of the 5’ leader catalyzed by ribonuclease P (RNase P). Human mitochondrial RNase P (mtRNase P) is composed of three protein subunits: mitochondrial RNase P protein (MRPP) 1, 2 and 3. Even though MRPP3 is the metallonuclease subunit responsible for catalysis, cleavage is observed only in the presence of the MRPP1/2 subcomplex. To understand the functional role of MRPP1/2, we reconstituted human mitochondrial RNase P in vitro and performed kinetic and thermodynamic analyses. MRPP1/2 significantly enhances both the catalytic activity and the apparent substrate affinity of mtRNase P. Additionally, pull-down and binding data demonstrate synergy between binding pre-tRNA and formation of a catalytically active MRPP1/2/3 complex. These data suggest that conformational changes in the MRPP1/2-pre-tRNA complex lead to protein-protein or protein-RNA interactions that increase both MRPP3 recognition and cleavage efficiency. This work presents the first kinetic model for human mtRNase P, providing a fundamental framework for the function of MRPP1/2 for recognition and processing of pre-tRNA. ER -