Localisation of the human hSuv3p helicase in the mitochondrial matrix and its preferential unwinding of dsDNA

• Published in: Nucleic acids research 2002-12, Vol.30 (23), p.5074-5086
• Main Authors: Minczuk, Michal, Piwowarski, Jan, Papworth, Monika A., Awiszus, Karen, Schalinski, Sarah, Dziembowski, Andrzej, Dmochowska, Aleksandra, Bartnik, Ewa, Tokatlidis, Kostas, Stepien, Piotr P., Borowski, Peter
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - metabolism; Amino Acid Sequence; Animals; COS Cells; DEAD-box RNA Helicases; DNA - metabolism; DNA Helicases - analysis; DNA Helicases - chemistry; DNA Helicases - metabolism; Escherichia coli - genetics; HeLa Cells; Humans; Mitochondria - enzymology; Mutation; Nucleic Acid Conformation; Protein Transport; RNA Helicases - analysis; RNA Helicases - chemistry; RNA Helicases - metabolism; Saccharomyces cerevisiae Proteins; Substrate Specificity; Yeasts - metabolism
• ISSN: 0305-1048; 1362-4962; 1362-4962
• DOI: 10.1093/nar/gkf647

We characterised the human hSuv3p protein belonging to the family of NTPases/helicases. In yeast mitochondria the hSUV3 orthologue is a component of the degradosome complex and participates in mtRNA turnover and processing, while in Caenorhabditis elegans the hSUV3 orthologue is necessary for viability of early embryos. Using immunofluorescence analysis, an in vitro mitochondrial uptake assay and sub‐fractionation of human mitochondria we show hSuv3p to be a soluble protein localised in the mitochondrial matrix. We expressed and purified recombinant hSuv3p protein from a bacterial expression system. The purified enzyme was capable of hydrolysing ATP with a Km of 41.9 µM and the activity was only modestly stimulated by polynucleotides. hSuv3p unwound partly hybridised dsRNA and dsDNA structures with a very strong preference for the latter. The presented analysis of the hSuv3p NTPase/helicase suggests that new functions of the protein have been acquired in the course of evolution.