Knockout and functional analysis of two DExD/H-box family helicase genes in Sulfolobus islandicus REY15A
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DExD/H-box helicases represent the largest family of helicases. They belong to superfamily 2 helicases and participate in nucleotide metabolism, ribosome biogenesis, and nucleocytoplasmic transport. The biochemical properties and structures of some DExD/H-box helicases in the archaea have been documented, but many of them have not been characterized; and reports on in vivo functional analyses are limited. In this study, we attempted gene knockout of 8 putative DExD/H-box helicases in Sulfolobus islandicus REY15A and obtained two deletion mutants, SiRe_0681 and SiRe_1605. We determined that ΔSiRe_0681 grew faster than wild type cells in the presence of methyl methanesulfonate (MMS). Flow cytometry analysis showed that this strain had fewer G1/S phase cells than the wild type, and the genes coding for cell division proteins were up-regulated. The stain ΔSiRe_1605 was more sensitive to MMS than the wild type cell, and many nucleotide metabolism and DNA repair enzymes were found to be down-regulated. Intriguingly, deletion of either gene led to silencing simultaneously of over 80 genes located at a specific region. This study provides a novel insight into the in vivo functions of predicted DExD/H-box family helicases in the archaea.
KeywordsArchaea Sulfolobus islandicus REY15A DExD/H-box helicases Gene knockout In vivo functions
We thank Dr. Qunxin She from University of Copenhagen for providing S. islandicus strains and the plasmid and all the members of our lab for helpful discussions. This work was supported by grants from the National Science Foundation of China (31470046 to Y.S. and 31470200 to J.N).
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