Structured RNAs and RNA–protein complexes (RNPs) fold through complex pathways that are replete with misfolded traps, and many RNAs and RNPs undergo extensive conformational changes during their functional cycles. These folding steps and conformational transitions are frequently promoted by RNA chaperone proteins, notably by superfamily 2 (SF2) RNA helicase proteins. The two largest families of SF2 helicases, DEAD-box and DEAH-box proteins, share evolutionarily conserved helicase cores, but unwind RNA helices through distinct mechanisms. Recent studies have advanced our understanding of how their distinct mechanisms enable DEAD-box proteins to disrupt RNA base pairs on the surfaces of structured RNAs and RNPs, while some DEAH-box proteins are adept at disrupting base pairs in the interior of RNPs. Proteins from these families use these mechanisms to chaperone folding and promote rearrangements of structured RNAs and RNPs, including the spliceosome, and may use related mechanisms to maintain cellular messenger RNAs in unfolded or partially unfolded conformations.
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Cover Image
Cover Image
Cryo-electron microscopy density map of a Cowpea Mosaic virus (CPMV) empty virus-like particle (eVLP) at 2.7 Å resolution (EMD-3952). The large (L) subunit is displayed in green and the small (S) subunit in blue. Five S subunits interact to form pronounced turrets at the 5-fold axis. Here we show a view down a two-fold axis. The eVLP was produced by transient co-expression in plants of the precursor of the L and S subunits (VP60) and the virus-encoded protease (24K) required for its processing. For further details, please see article by Lomonossoff et al, pages 1263–1269
Distinct RNA-unwinding mechanisms of DEAD-box and DEAH-box RNA helicase proteins in remodeling structured RNAs and RNPs
Benjamin Gilman, Pilar Tijerina, Rick Russell; Distinct RNA-unwinding mechanisms of DEAD-box and DEAH-box RNA helicase proteins in remodeling structured RNAs and RNPs. Biochem Soc Trans 15 December 2017; 45 (6): 1313–1321. doi: https://doi.org/10.1042/BST20170095
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