Vasara T, Saloheimo M, Keränen S, Penttilä M
VTT Biotechnology, Finland.
Curr Genet. 2001 Sep;40(2):119-27. doi: 10.1007/s002940100245.
The Trichoderma reesei gene, rho3, encoding the functional homologue of the Saccharomyces cerevisiae small GTP-binding protein Rho3p was cloned as a suppressor of the secretion-deficient mutation sec15-1 in yeast. The encoded protein showed 61% amino acid identity to the Rho3 protein. Rescue of the growth defect of a RHO3 disruption strain by an expression vector carrying rho3 cDNA confirmed the functional homology with the S. cerevisiae RHO3 gene. In addition, overproduction of T. reesei RHOIII in this yeast strain appeared to improve the actin organization and chitin localization of the cells. Three putative mutant (rho3Gly20Val alleles of the T. reesei rho3 gene rho3 Thr25Asn, rho3Asp12Ala) were introduced into the wild-type yeast, in yeast with sec15 mutation and in yeast with Rho3p depletion. Cells expressing rho3Gly20Val displayed wild-type growth and those expressing rho3 Thr25Asn and rho3Asp126Ala had a loss-of-function phenotype.
里氏木霉基因rho3编码酿酒酵母小GTP结合蛋白Rho3p的功能同源物，该基因作为酵母分泌缺陷型突变体sec15-1的抑制子被克隆。编码的蛋白质与Rho3蛋白有61%的氨基酸同一性。携带rho3 cDNA的表达载体对RHO3缺失菌株生长缺陷的挽救证实了其与酿酒酵母RHO3基因的功能同源性。此外，在该酵母菌株中过量表达里氏木霉RHOIII似乎改善了细胞的肌动蛋白组织和几丁质定位。将里氏木霉rho3基因的三个推定突变体（rho3 Gly20Val、rho3 Thr25Asn、rho3 Asp126Ala等位基因）导入野生型酵母、具有sec15突变的酵母和Rho3p缺失的酵母中。表达rho3 Gly20Val的细胞表现出野生型生长，而表达rho3 Thr25Asn和rho3 Asp126Ala的细胞具有功能丧失表型。
