Role of the RRM domain in the activity, structure and stability of poly(A)-specific ribonuclease.
Poly(A) specific ribonuclease (PARN), which contains a catalytic domain and two RNA-binding domains (R3H and RRM), acts as a key enzyme in eukaryotic organisms to regulate the stability of mRNA by degrading the 3' poly-(A) tail. In this research, the activity, structure and stability were compared between the full-length 74kDa PARN, the proteolytic 54kDa fragment with half of the RRM, and a truncated 46kDa form completely missing the RRM. The results indicated that the 46kDa one had the lowest activity and substrate binding affinity, the most hydrophobic exposure in the native state and the least stability upon denaturation. The dissimilarity in the activity, structure and stability of the three PARNs revealed that the entire RRM domain not only contributed to the substrate binding and efficient catalysis of PARN, but also stabilized the overall structures of the protein. Spectroscopic experiments suggested that the RRM domain might be structurally adjacent to the R3H domain, and thus provide a basis for the cooperative binding of poly(A) by the two RNA-binding domains as well as the catalytic domain.
Zhang
Ao
A
State Key Laboratory of Biomembrane and Membrane Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, PR China.
Liu
Wei-Feng
WF
Yan
Yong-Bin
YB
D001665:Binding Sites; D002384:Catalysis; D020134:Catalytic Domain; D004795:Enzyme Stability; D005095:Exoribonucleases / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D005095:Exoribonucleases; D016601:RNA-Binding Proteins