Acts as an RNA chaperone to resolve non-native structures formed during RNA folding to promote mitochondrial group I, but also group II, intron splicing. Functions predominantly by disrupting accessible RNA secondary structure and depends on spontaneous openings in tightly packed RNAs to gain access to RNA helices. ATP + H2O = ADP + H(+) + phosphate Activated by exposed helices in a group I intron RNA. The C-ter region (residues 578-626) is not directly involved in DNA unwinding activity but functions by tethering cyt-19 to structured RNAs, so that it can efficiently disrupt exposed, non-native structural elements, allowing them to refold. The Q motif is unique to and characteristic of the DEAD box family of RNA helicases and controls ATP binding and hydrolysis. Belongs to the DEAD box helicase family.