This domain contains a P-loop (Walker A) motif, suggesting that it has ATPase activity, and a Walker B motif. In tRNA(Met) cytidine acetyltransferase (TmcA) it may function as an RNA helicase motor (driven by ATP hydrolysis) which delivers the wobble base to the active centre of the GCN5-related N-acetyltransferase (GNAT) domain [1]. It is found in the bacterial exodeoxyribonuclease V alpha chain (RecD), which has 5'-3' helicase activity. It is structurally similar to the motor domain 1A in other SF1 helicases [2].

1: RNA helicase module in an acetyltransferase that modifies a specific tRNA anticodon. Chimnaronk S, Suzuki T, Manita T, Ikeuchi Y, Yao M, Suzuki T, Tanaka I; EMBO J. 2009;28:1362-1373. PMID:19322199

2: Crystal structure of RecBCD enzyme reveals a machine for processing DNA breaks. Singleton MR, Dillingham MS, Gaudier M, Kowalczykowski SC, Wigley DB; Nature. 2004;432:187-193. PMID:15538360