Major helicase player in mitochondrial RNA metabolism. Component of the mitochondrial degradosome (mtEXO) complex, that degrades 3' overhang double-stranded RNA with a 3'-to-5' directionality in an ATP-dependent manner (By similarity). ATPase and ATP-dependent multisubstrate helicase, able to unwind double-stranded (ds) DNA and RNA, and RNA/DNA heteroduplexes in the 5'-to-3' direction (PubMed:23808500). Plays a role in the RNA surveillance system in mitochondria; regulates the stability of mature mRNAs, the removal of aberrantly formed mRNAs and the rapid degradation of non coding processing intermediates (By similarity). Confers salinity and drought stress tolerances by maintaining both photosynthesis and antioxidant machinery, probably via an increase in plant hormones levels such as gibberellic acid (GA(3)), the cytokinin zeatin (Z) and indole-3-acetic acid (IAA) (PubMed:23808500, PubMed:25184028). ATP + H2O = ADP + H(+) + phosphate Homodimer; in free form. Component of the mitochondrial degradosome (mtEXO) complex which is a heteropentamer containing 2 copies of SUPV3L1 and 3 copies of PNPT1. Induced in seedlings in response to high levels of salt. Belongs to the helicase family.