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Medientyp:
E-Artikel
Titel:
The G-patch protein Spp2 couples the spliceosome-stimulated ATPase activity of the DEAH-box protein Prp2 to catalytic activation of the spliceosome
Beschreibung:
<jats:p>Structural rearrangement of the activated spliceosome (B<jats:sup>act</jats:sup>) to yield a catalytically active complex (B*) is mediated by the DEAH-box NTPase Prp2 in cooperation with the G-patch protein Spp2. However, how the energy of ATP hydrolysis by Prp2 is coupled to mechanical work and what role Spp2 plays in this process are unclear. Using a purified splicing system, we demonstrate that Spp2 is not required to recruit Prp2 to its bona fide binding site in the B<jats:sup>act</jats:sup> spliceosome. In the absence of Spp2, the B<jats:sup>act</jats:sup> spliceosome efficiently triggers Prp2’s NTPase activity, but NTP hydrolysis is not coupled to ribonucleoprotein (RNP) rearrangements leading to catalytic activation of the spliceosome. Transformation of the B<jats:sup>act</jats:sup> to the B* spliceosome occurs only when Spp2 is present and is accompanied by dissociation of Prp2 and a reduction in its NTPase activity. In the absence of spliceosomes, Spp2 enhances Prp2’s RNA-dependent ATPase activity without affecting its RNA affinity. Our data suggest that Spp2 plays a major role in coupling Prp2’s ATPase activity to remodeling of the spliceosome into a catalytically active machine.</jats:p>