An Extracellular S1Type Nuclease of Marine Fungus

Authors: Larissa A Balabanova Yury M Gafurov Mikhael V Pivkin Natalya A Terentyeva Galina N Likhatskaya Valery A Rasskazov

Publish Date: 2011/06/07

Volume: 14, Issue: 1, Pages: 87-95

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Abstract

An extracellular nuclease was purified 165fold with a specific activity of 41250 U/mg polyU by chromatography with modified chitosan from the culture of marine fungus Penicillium melinii isolated from colonial ascidium collected near Shikotan Island Sea of Okhotsk at a depth of 123 m The purified nuclease is a monomer with the molecular weight of 35 kDa The enzyme exhibits maximum activity at pH 37 for DNA and RNA The enzyme is stable until 75°C and in the pH range of 25–80 The enzyme endonucleolytically degrades ssDNA and RNA by 3′–5′ mode to produce 5′oligonucleotides and 5′mononucleotides however it preferentially degrades polyU The enzyme can digest dsDNA in the presence of pregnancyspecific beta1glycoprotein1 The nuclease acts on closed circular doublestranded DNA to produce opened circular DNA and then the linear form DNA by singlestrand scission DNA sequence encoding the marine fungus P melinii endonuclease revealed homology to S1type nucleases The tight correlation found between the extracellular endonuclease activity and the rate of H3thymidine uptake by actively growing P melinii cells suggests that this nuclease is required for fulfilling the nucleotide pool of precursors of DNA biosynthesis during the transformation of hyphae into the aerial mycelium and conidia in stressful environmental conditions

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