ATP-dependent RNA helicase that associates with the RNA exosome complex, with the cap binding complex (CBC) and with the NEXT-like complex. Involved in the degradation of a large number of non-coding nuclear exosome substrates such as snoRNA and miRNA precursors, incompletely spliced mRNAs, and spurious transcripts produced from pseudogenes and intergenic regions (PubMed:25144737). Involved in the maintenance of homeotic B and C gene expression in the reproductive whorls. Regulates floral organ spacing and identity, probably through the regulation of protein synthesis or mRNA degradation (PubMed:11923195). ATP + H2O = ADP + H(+) + phosphate Expressed in inflorescences, leaves, stems, and roots. Expressed in specific patterns in the inflorescence meristem and developing flowers. Present throughout the inflorescence meristem and in young floral meristems through stage 4. Around stage 5, present within the developing organs of the inner three whorls but absent from sepals. At later stage of floral development, present at a low level in the gynoecium but accumulate strongly in developing ovules. When combined with mutations in HUA1 and HUA2, reduced stem elongation and alterations in production of flowers along the inflorescence. These flowers are characterized by the presence of third whorl sepal-petal-stamens and fourth whorl sepal-carpels leading to abnormal floral organ number and positioning. Over-accumulation of non-coding nuclear exososome targets (PubMed:25144737). Belongs to the DExH box helicase family. SKI2 subfamily. Truncated N-terminus.