It is known, from the zymogram method of nuclease activity assay, that the crude extracts of Cunninghamella echinulata var. echinulata contained at least three distinct extracellular nucleases. Among them, the major form was 30 kDa in molecular mass and termed nuclease C1. In this report, nuclease C1 was purified to apparent homogeneity by chromatography on Cibacron blue-3GA, phenyl-Sepharose 4B and HiTrap Heparin. Nuclease C1 acquired enzymatic activity in the presence of Mn 2ϩ or Mg 2ϩ and was inhibited by EDTA. The activity was maximal at pH 7Ϫ8.5. The primary structure of nuclease C1 was completely determined using enzymatic digestion and gene cloning. The N-terminal 49 residues of nuclease C1 were first elucidated from a tryptic digest. Two degenerate upstream primers were subsequently designed to amplify the cDNA encoding nuclease C1. The resulting protein sequence of nuclease C1 was shown to be composed of 252 residues. It was intriguing to find that the protein sequence of nuclease C1 showed significant similarities with the sequences of the mitochondrial nucleases of Saccharomyces cerevisiae (44% identity) and Schizosaccharomyces pombe (42 % identity). Residue His87 of nuclease C1 was postulated to be located at the active site from sequence similarity with secreted nuclease from Serratia marcescens.Keywords : nuclease C1; mitochondrial nuclease ; Cunninghamella echinulata ; Saccharomyces cerevisiae; Schizosaccharomyces pombe.Nucleases act on both DNA and RNA to release products containing 5′-or 3′-phosphates [1]. Several fungal species are known to produce both extracellular and intracellular nucleases. Representatives of extracellular fungal nucleases are nuclease S1 of Aspergillus oryzae [2,3] and nuclease P1 of Penicillium citrinum [4,5]. The properties and the structures of these two nucleases are well characterized. Other fungi also secrete nucleases, e.g. Neurospora crassa and Aspergillus nidulans, which are referred to as DNase (deoxyribonuclease) A [6] and DNase 4 [7], respectively.Clinically, some Cunninghamella species cause severe syndromes and even led to death in humans. For example, several reports have indicated that Cunninghamella bertholletiae can infect patients with cancer and immunocompromise children [8,9]. Diseases including paranasal sinusitus [10] and mucormycosis [11] have been relatively correlated with Cunninghamella infection. The most important risk factors for C. bertholletiae infection include corticosteroid administration and pro-
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.