1. An antifungal protein from Ginkgo biloba binds actin and can trigger cell death
Ningning Gao, Parvesh Wadhwani, Philipp Mühlhäuser, Qiong Liu, Michael Riemann, Anne S Ulrich, Peter Nick Protoplasma. 2016 Jul;253(4):1159-74. doi: 10.1007/s00709-015-0876-4. Epub 2015 Aug 28.
Ginkbilobin is a short antifungal protein that had been purified and cloned from the seeds of the living fossil Ginkgo biloba. Homologues of this protein can be detected in all seed plants and the heterosporic fern Selaginella and are conserved with respect to domain structures, peptide motifs, and specific cysteine signatures. To get insight into the cellular functions of these conserved motifs, we expressed green fluorescent protein fusions of full-length and truncated ginkbilobin in tobacco BY-2 cells. We show that the signal peptide confers efficient secretion of ginkbilobin. When this signal peptide is either cleaved or masked, ginkbilobin binds and visualizes the actin cytoskeleton. This actin-binding activity of ginkbilobin is mediated by a specific subdomain just downstream of the signal peptide, and this subdomain can also coassemble with actin in vitro. Upon stable overexpression of this domain, we observe a specific delay in premitotic nuclear positioning indicative of a reduced dynamicity of actin. To elucidate the cellular response to the binding of this subdomain to actin, we use chemical engineering based on synthetic peptides comprising different parts of the actin-binding subdomain conjugated with the cell-penetrating peptide BP100 and with rhodamine B as a fluorescent reporter. Binding of this synthetic construct to actin efficiently induces programmed cell death. We discuss these findings in terms of a working model, where ginkbilobin can activate actin-dependent cell death.
3. Ginkbilobin, a novel antifungal protein from Ginkgo biloba seeds with sequence similarity to embryo-abundant protein
H Wang, T B Ng Biochem Biophys Res Commun. 2000 Dec 20;279(2):407-11. doi: 10.1006/bbrc.2000.3929.
A novel single-chained antifungal protein with a molecular weight of 13 kDa displaying an N-terminal sequence with marked similarity to embryo-abundant protein from the white spruce was isolated from the seeds of Ginkgo biloba using ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Sepharose, and then gel filtration on Superdex 75. The protein, designated ginkbilobin, exerted potent antifungal activity against a variety of fungi, including Botrytis cinerea, Mycosphaerella arachidicola, Fusarium oxysporum, Rhizoctonia solani, and Coprinus comatus. Ginkbilobin exhibited a moderate antibacterial action against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. It suppressed the activity of HIV-1 reverse transcriptase and the proliferation of murine splenocytes.
