Aréchiga-Carvajal Elva T, Ruiz-Herrera José
Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados del IPN Unidad Irapuato, Km. 9.6 Libramiento Norte, Carretera Irapuato-León, 36500 Irapuato, Gto., México.
Eukaryot Cell. 2005 Jun;4(6):999-1008. doi: 10.1128/EC.4.6.999-1008.2005.
A homologue of the gene encoding the transcription factor Rim101 (PacC), involved in pH signal transduction in fungi, was identified in the pathogenic basidiomycete Ustilago maydis. The gene (RIM101) encodes a protein of 827 amino acid residues, which shows highest similarity to PacC proteins from Fusarium oxysporum and Aspergillus niger. The gene had the capacity to restore protease activity to rim101 mutants from Yarrowia lipolytica, confirming its homologous function, and was expressed at both acid and neutral pH. Null Deltarim101 mutants were not affected in the in vitro pH-induced dimorphic transition, their growth rate, resistance to hypertonic sorbitol or KCl stress, and pathogenicity. However, similar to pacC (rim101) mutants in other fungi, they displayed a pleiotropic phenotype with alterations in morphogenesis, impairment in protease secretion, and increased sensitivity to Na+ and Li+ ions. Other phenotypic characteristics not previously reported in fungal pacC (rim101) mutants (morphological changes, increased sensitivity to lytic enzymes, and augmented polysaccharide secretion) were also observed in U. maydis mutants. All these modifications were alleviated by transformation with the wild-type gene, confirming that all were the result of mutation in RIM101. These data indicate that the Pal/Rim pathway is functional in U. maydis (and probably in other basidiomycetes) and plays complex roles in pH-sensing phenomena, as occurs in ascomycetes and deuteromycetes.
在致病担子菌玉米黑粉菌中鉴定出了编码转录因子Rim101（PacC）的基因的一个同源物，该转录因子参与真菌中的pH信号转导。该基因（RIM101）编码一个含有827个氨基酸残基的蛋白质，它与尖孢镰刀菌和黑曲霉的PacC蛋白具有最高的相似性。该基因能够恢复解脂耶氏酵母rim101突变体的蛋白酶活性，证实了其同源功能，并且在酸性和中性pH条件下均有表达。RIM101缺失突变体在体外pH诱导的双态转变、生长速率、对高渗山梨醇或KCl胁迫的抗性以及致病性方面均未受到影响。然而，与其他真菌中的pacC（rim101）突变体类似，它们表现出多效性表型，包括形态发生改变、蛋白酶分泌受损以及对Na+和Li+离子的敏感性增加。在玉米黑粉菌突变体中还观察到了其他真菌pacC（rim101）突变体中未曾报道过的表型特征（形态变化、对裂解酶的敏感性增加以及多糖分泌增加）。所有这些修饰通过野生型基因转化得以缓解，证实了所有这些都是RIM101突变的结果。这些数据表明Pal/Rim途径在玉米黑粉菌（可能也在其他担子菌中）中发挥作用，并且在pH感知现象中发挥复杂作用，就像在子囊菌和半知菌中一样。
