Evolutionary Conservation of the Ribosomal Biogenesis Factor Rbm19/Mrd1: Implications for Function


Ribosome biogenesis in eukaryotes requires coordinated folding and assembly of a pre-rRNA into sequential pre-rRNA-protein complexes in which chemical modifications and RNA cleavages occur. These processes require many small nucleolar RNAs (snoRNAs) and proteins. Rbm19/Mrd1 is one such protein that is built from multiple RNA-binding domains (RBDs). We find that Rbm19/Mrd1 with five RBDs is present in all branches of the eukaryotic phylogenetic tree, except in animals and Choanoflagellates, that instead have a version with six RBDs and Microsporidia which have a minimal Rbm19/Mrd1 protein with four RBDs. Rbm19/Mrd1 therefore evolved as a multi-RBD protein very early in eukaryotes. The linkers between the RBDs have conserved properties; they are disordered, except for linker 3, and position the RBDs at conserved relative distances from each other. All but one of the RBDs have conserved properties for RNA-binding and each RBD has a specific consensus sequence and a conserved position in the protein, suggesting a functionally important modular design. The patterns of evolutionary conservation provide information for experimental analyses of the function of Rbm19/Mrd1. In vivo mutational analysis confirmed that a highly conserved loop 5-β4-strand in RBD6 is essential for function.

DOI: 10.1371/journal.pone.0043786

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@inproceedings{Kallberg2012EvolutionaryCO, title={Evolutionary Conservation of the Ribosomal Biogenesis Factor Rbm19/Mrd1: Implications for Function}, author={Yvonne Kallberg and {\AA}sa Segerstolpe and Fredrik Lackmann and Bengt Persson and Lars Wieslander}, booktitle={PloS one}, year={2012} }