NOPCHAP1 is a PAQosome cofactor that helps loading NOP58 on RUVBL1/2 during box C/D snoRNP biogenesis.

Nucleic acids research 2021 Jan 25

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The PAQosome is a large complex composed of the HSP90/R2TP chaperone and a prefoldin-like module. It promotes the biogenesis of cellular machineries but it is unclear how it discriminates closely related client proteins. Among the main PAQosome clients are C/D snoRNPs and in particular their core protein NOP58. Using NOP58 mutants and proteomic experiments, we identify different assembly intermediates and show that C12ORF45, which we rename NOPCHAP1, acts as a bridge between NOP58 and PAQosome. NOPCHAP1 makes direct physical interactions with the CC-NOP domain of NOP58 and domain II of RUVBL1/2 AAA+ ATPases. Interestingly, NOPCHAP1 interaction with RUVBL1/2 is disrupted upon ATP binding. Moreover, while it robustly binds both yeast and human NOP58, it makes little interactions with NOP56 and PRPF31, two other closely related CC-NOP proteins. Expression of NOP58, but not NOP56 or PRPF31, is decreased in NOPCHAP1 KO cells. We propose that NOPCHAP1 is a client-loading PAQosome cofactor that selects NOP58 to promote box C/D snoRNP assembly. © The Author(s) 2020. Published by Oxford University Press on behalf of Nucleic Acids Research.

Citation

Yoann Abel, Ana C F Paiva, Jonathan Bizarro, Marie-Eve Chagot, Paulo E Santo, Marie-Cécile Robert, Marc Quinternet, Franck Vandermoere, Pedro M F Sousa, Philippe Fort, Bruno Charpentier, Xavier Manival, Tiago M Bandeiras, Edouard Bertrand, Céline Verheggen. NOPCHAP1 is a PAQosome cofactor that helps loading NOP58 on RUVBL1/2 during box C/D snoRNP biogenesis. Nucleic acids research. 2021 Jan 25;49(2):1094-1113