title: Novel anticandidal activity of a recombinant Lampetra japonica RGD3 protein.
abstract: Lj-RGD3, an RGD (Arg-Gly-Asp) toxin protein from the salivary gland of Lampetra japonica, exhibits antifungal activity against Candida albicans. Lj-RGD3 has three RGD motifs and shows homology to histidine-rich glycoprotein. We synthesised two mutant derivatives of Lj-RGD3: Lj-26, which lacks all three RGD motifs and contains no His residues; and Lj-112, which lacks only the three RGD motifs. We investigated the effects of the wild-type and mutated toxins on a gram-positive bacterium (Escherichia coli), a gram-negative bacterium (Staphylococcus aureus), and a fungus (C. albicans). rLj-RGD3 and its mutants exhibited antifungal but not antibacterial activity, as measured by a radial diffusion assay. The C. albicans inhibition zone induced by rLj-112 was larger than that induced by the other proteins, and its inhibitory effect on C. albicans was dose-dependent. In viable-count assays, the rLj-112 MIC was 7.7 micrometer, whereas the MIC of the positive control (ketoconazole) was 15 micrometer. Time-kill kinetics demonstrated that rLj-112 effectively killed C. albicans at 1× and 2× MIC within 12 and 6 h, respectively. Electron microscopy analysis showed that rLj-RGD3 and rLj-112 induced C. albicans lysis. Our results demonstrate a novel anticandidal activity for rLj-RGD3 and its mutant derivatives.
authors.affiliation: Liaoning Provincial Key Labouratory of Biotechnology and Drug Discovery, Department of Biological Sciences, Liaoning Normal University, Dalian 116029, P. R. China.
authors.forename: Caiping
authors.initials: C
authors.lastname: Wu
authors.forename: Li
authors.initials: L
authors.lastname: Lu
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Rong
authors.initials: R
authors.lastname: Xiao
authors.forename: Jihong
authors.initials: J
authors.lastname: Wang
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D001483:Base Sequence; D002175:Candida / Q000187:drug effects; D005397:Fish Venoms / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009842:Oligopeptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D016415:Sequence Alignment
chemical_list: D000935:Antifungal Agents; D005397:Fish Venoms; D009842:Oligopeptides; C574387:RGD3 protein, Lampetra japonica; D011994:Recombinant Proteins