Instituto Venezolano de Investigaciones Científicas, Centro de Microbiología y Biología Celular, Caracas, Venezuela.
Med Mycol. 2010 Feb;48(1):35-47. doi: 10.3109/13693780802713356.
In this report we identified orthologues of fungal AGS1, RHO1, RHO2, RAC1 and CDC42 genes in the dimorphic fungus Paracoccidioides brasiliensis. Based on its homology to known fungal sequences, P. brasiliensis Ags1 was identified as an alpha-1,3-glucan synthase, while Rho1, Rho2, Rac1 and Cdc42 proteins were classified into the Rho1, Rho2, Rac1 and Cdc42 subgroups of fungal Rho GTPases, respectively. Of them, Rho1 is one of two subunits of a putative beta-1,3-glucan synthase complex, the other being the synthase itself (Fks1), while Rho2 has been associated to the alpha-1,3-glucan synthase (Ags1). Expression studies showed that mRNAs levels of RHO2 and AGS1 kept a direct relationship but the levels of RHO1 and FKS1 did not. P. brasiliensis RHO1 successfully restored growth of Saccharomyces cerevisiae rho1 mutant under restrictive temperature conditions. Chemical analyses of P. brasiliensis alpha-1,3-glucan, synthesized by Ags1p, indicated that it is essentially a linear polysaccharide, with <3% of alpha-1,4-linked glucose branches, occasionally attached as single units to the alpha-1,3-backbone.
在本报告中，我们鉴定了二相性真菌巴西副球孢子菌中真菌 AGS1、RHO1、RHO2、RAC1 和 CDC42 基因的同源物。根据与已知真菌序列的同源性，巴西副球孢子菌 Ags1 被鉴定为一种α-1,3-葡聚糖合酶，而 Rho1、Rho2、Rac1 和 Cdc42 蛋白分别被归类为真菌 Rho GTPases 的 Rho1、Rho2、Rac1 和 Cdc42 亚群。其中，Rho1 是假定的β-1,3-葡聚糖合酶复合物的两个亚基之一，另一个是该合酶本身（Fks1），而 Rho2 与α-1,3-葡聚糖合酶（Ags1）有关。表达研究表明，RHO2 和 AGS1 的 mRNA 水平保持直接关系，但 RHO1 和 FKS1 的水平没有。巴西副球孢子菌 RHO1 成功地在限制温度条件下恢复了酿酒酵母 rho1 突变体的生长。通过 Ags1p 合成的巴西副球孢子菌α-1,3-葡聚糖的化学分析表明，它本质上是一种线性多糖，只有<3%的α-1,4 连接的葡萄糖支链，偶尔作为单单元附着在α-1,3-主链上。
