西亚试剂优势供应上万种化学试剂产品，欢迎各位新老客户咨询、选购！
中国
联系我们
联系方式：400-990-3999 / 邮箱：sales@xiyashiji.com
西亚试剂 —— 品质可靠，值得信赖
Structural basis for the modular recognition of single-stranded RNA by PPR proteins
Ping Yin，Quanxiu Li，Chuangye Yan，Ying Liu，Junjie Liu，Feng Yu，Zheng Wang，Jiafu Long，Jianhua He，Hong-Wei Wang，Jiawei Wang，Jian-Kang Zhu，Yigong Shi& Nieng Yan
Pentatricopeptide repeat (PPR) proteins represent a large family of sequence-specific RNA-binding proteins that are involved in multiple aspects of RNA metabolism. PPR proteins， which are found in exceptionally large numbers in the mitochondria and chloroplasts of terrestrial plants1， 2， 3， 4， 5， recognize single-stranded RNA (ssRNA) in a modular fashion6， 7， 8. The maize chloroplast protein PPR10 binds to two similar RNA sequences from the ATPI–ATPH and PSAJ–RPL33 intergenic regions， referred to as ATPH and PSAJ， respectively9， 10. By protecting the target RNA elements from 5′ or 3′ exonucleases， PPR10 defines the corresponding 5′ and 3′ messenger RNA termini9， 10， 11. Despite rigorous functional characterizations， the structural basis of sequence-specific ssRNA recognition by PPR proteins remains to be elucidated. Here we report the crystal structures of PPR10 in RNA-free and RNA-bound states at resolutions of 2.85 and 2.45， respectively. In the absence of RNA binding， the nineteen repeats of PPR10 are assembled into a right-handed superhelical spiral. PPR10 forms an antiparallel， intertwined homodimer and exhibits considerable conformational changes upon binding to its target ssRNA， an 18-nucleotide PSAJ element. Six nucleotides of PSAJ are specifically recognized by six corresponding PPR10 repeats following the predicted code. The molecular basis for the specific and modular recognition of RNA bases A， G and U is revealed. The structural elucidation of RNA recognition by PPR proteins provides an important framework for potential biotechnological applications of PPR proteins in RNA-related research areas.
