Garrigues Sandra, Marcos Jose F, Manzanares Paloma, Gandía Mónica
Food Biotechnology Department, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), 46980 Paterna, Valencia, Spain.
J Fungi (Basel). 2020 Oct 2;6(4):203. doi: 10.3390/jof6040203.
Antifungal proteins (AFPs) from ascomycete fungi could help the development of antimycotics. However, little is known about their biological role or functional interactions with other fungal biomolecules. We previously reported that AfpB from the postharvest pathogen cannot be detected in the parental fungus yet is abundantly produced biotechnologically. While aiming to detect AfpB, we identified a conserved and novel small Secreted Cysteine-rich Anionic (Sca) protein, encoded by the gene PDIG_23520 from CECT 20796. The gene is expressed during culture and early during citrus fruit infection. Both null mutant (Δ) and Sca overproducer (Sca) strains show no phenotypic differences from the wild type. Sca is not antimicrobial but potentiates growth when added in high amounts and enhances the in vitro antifungal activity of AfpB. The Sca strain shows increased incidence of infection in citrus fruit, similar to the addition of purified Sca to the wild-type inoculum. Sca compensates and overcomes the protective effect of AfpB and the antifungal protein PeAfpA from the apple pathogen in fruit inoculations. Our study shows that Sca is a novel protein that enhances the growth and virulence of its parental fungus and modulates the activity of AFPs.
子囊菌纲真菌中的抗真菌蛋白（AFP）有助于抗真菌药物的研发。然而，对于它们的生物学作用或与其他真菌生物分子的功能相互作用却知之甚少。我们之前报道过，采后病原菌中的AfpB在亲本真菌中无法检测到，但通过生物技术大量产生。在旨在检测AfpB的过程中，我们鉴定出一种保守且新颖的小分泌富含半胱氨酸阴离子（Sca）蛋白，由来自CECT 20796的基因PDIG_23520编码。该基因在培养期间以及柑橘果实感染早期表达。缺失突变体（Δ）和Sca过量产生菌株（Sca）与野生型均无表型差异。Sca不具有抗菌性，但大量添加时可促进生长，并增强AfpB的体外抗真菌活性。Sca菌株在柑橘果实中的感染发生率增加，类似于向野生型接种物中添加纯化的Sca。在果实接种中，Sca补偿并克服了AfpB和来自苹果病原菌的抗真菌蛋白PeAfpA的保护作用。我们的研究表明，Sca是一种新型蛋白，可增强其亲本真菌的生长和毒力，并调节AFP的活性。
