Isomerases;
Isomerases altering macromolecular conformation;
Enzymes altering nucleic acid conformation
BRITE hierarchy

RNA 3'-5' helicase (ATP-hydrolysing)

n ATP + n H2O + wound RNA = n ADP + n phosphate + unwound RNA

ATP [CPD:C00002];
H2O [CPD:C00001];
wound RNA

RNA helicases, which participate in nearly all aspects of RNA metabolism, utilize the energy from ATP hydrolysis to unwind RNA. The engine core of helicases is usually made of a pair of RecA-like domains that form an NTP binding cleft at their interface. Changes in the chemical state of the NTP binding cleft (binding of the NTP or its hydrolysis products) alter the relative positions of the RecA-like domains and nucleic acid-binding domains, creating structural motions that disrupt the pairing of the nucleic acid, causing separation and unwinding. Most RNA helicases utilize a mechanism known as canonical duplex unwinding, in which the helicase binds to a single stranded region adjacent to the duplex and then translocates along the bound strand with defined directionality, displacing the complementary strand. Most of these helicases proceed 3' to 5' (type A polarity), but some proceed 5' to 3' (type B polarity - cf. EC 5.6.2.5, RNA 5'-3' helicase), and some are able to catalyse unwinding in either direction [1,3]. Most canonically operating helicases require substrates with single stranded regions in a defined orientation (polarity) with respect to the duplex. A different class of RNA helicases, EC 5.6.2.7, DEAD-box RNA helicase, use a different mechanism and unwind short stretches of RNA with no translocation.

EC 5.6.2.6 created 2024 (EC 3.6.4.13 created 2009, part incorporated 2024)