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A divergent Pumilio repeat protein family for pre-rRNA processing and mRNA localization
- Qiu, Chen, McCann, Kathleen L., Wine, Robert N., Baserga, Susan J., Hall, Traci M. Tanaka
- Proceedings of the National Academy of Sciences of the United States of America 2014 v.111 no.52 pp. 18554-18559
- DNA, RNA-binding proteins, double-stranded RNA, feminization, humans, messenger RNA, nucleotide sequences, translation (genetics), yeasts
- Pumilio/feminization of XX and XO animals (fem)-3 mRNA-binding factor (PUF) proteins bind sequence specifically to mRNA targets using a single-stranded RNA-binding domain comprising eight Pumilio (PUM) repeats. PUM repeats have now been identified in proteins that function in pre-rRNA processing, including human Puf-A and yeast Puf6. This is a role not previously ascribed to PUF proteins. Here we present crystal structures of human Puf-A that reveal a class of nucleic acid-binding proteins with 11 PUM repeats arranged in an “L”-like shape. In contrast to classical PUF proteins, Puf-A forms sequence-independent interactions with DNA or RNA, mediated by conserved basic residues. We demonstrate that equivalent basic residues in yeast Puf6 are important for RNA binding, pre-rRNA processing, and mRNA localization. Thus, PUM repeats can be assembled into alternative folds that bind to structured nucleic acids in addition to forming canonical eight-repeat crescent-shaped RNA-binding domains found in classical PUF proteins.