RESUMEN
Morphological development of the fungal pathogen Candida albicans is profoundly affected by ambient pH. Acidic pH restricts growth to the yeast form, whereas neutral pH permits development of the filamentous form. Superimposed on the pH restriction is a temperature requirement of approximately 37 degrees C for filamentation. The role of pH in development was investigated by selecting revertants of phr2Delta mutants that had gained the ability to grow at acid pH. The extragenic suppressors in two independent revertants were identified as nonsense mutations in the pH response regulator RIM101 (PRR2) that resulted in a carboxy-terminal truncation of the open reading frame. These dominant active alleles conferred the ability to filament at acidic pH, to express PHR1, an alkaline-expressed gene, at acidic pH, and to repress the acid-expressed gene PHR2. It was also observed that both the wild-type and mutant alleles could act as multicopy suppressors of the temperature restriction on filamentation, allowing extensive filamentation at 29 degrees C. The ability of the activated alleles to promote filamentation was dependent upon the developmental regulator EFG1. The results suggest that RIM101 is responsible for the pH dependence of hyphal development.
Asunto(s)
Candida albicans/fisiología , Proteínas de Unión al ADN/genética , Proteínas Fúngicas/genética , Genes Dominantes , Glicoproteínas de Membrana , Factores de Transcripción , Apoenzimas/genética , Apoenzimas/metabolismo , División Celular/genética , Proteínas de Unión al ADN/metabolismo , Desoxirribodipirimidina Fotoliasa/genética , Desoxirribodipirimidina Fotoliasa/metabolismo , Proteínas Fúngicas/metabolismo , Dosificación de Gen , Regulación Fúngica de la Expresión Génica , Heterocigoto , Concentración de Iones de Hidrógeno , Mutación , Supresión GenéticaRESUMEN
The functionality of beta-galactosidase encoded by the E. coli lacZ gene as a reporter of gene expression in C. glabrata was investigated. C. glabrata/E. coli shuttle vectors were constructed, containing both a C. glabrata CEN-ARS cassette, to allow regular segregation and episomal replication of the plasmids, and the lacZ coding sequence of E. coli. The functionality of beta-galactosidase in C. glabrata was verified by inserting the promoter and the 5' coding region of the HIS3 gene from C. glabrata directionally upstream of the lacZ gene. By fusing the promoter of the copper-controlled MTII gene to the lacZ reporter, we showed that beta-galactosidase activity can be differentially induced in C. glabrata. beta-galactosidase reporter activities were detected qualitatively by an indirect filter assay and quantitatively from permeabilized cells.
Asunto(s)
Candida/genética , Vectores Genéticos/genética , Operón Lac/genética , beta-Galactosidasa/genética , Centrómero/genética , Sulfato de Cobre/farmacología , ADN de Hongos/genética , ADN Recombinante , Relación Dosis-Respuesta a Droga , Escherichia coli/genética , Proteínas Fúngicas/genética , Expresión Génica/efectos de los fármacos , Genes Reporteros/genética , Hidroliasas/genética , Metalotioneína/genética , Plásmidos , Proteínas Recombinantes de Fusión/efectos de los fármacos , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Replicón/genética , beta-Galactosidasa/efectos de los fármacos , beta-Galactosidasa/metabolismoRESUMEN
A case of uterine leiomyosarcoma with cerebral and pulmonary metastasis is presented. The patient underwent chemotherapy and multiple surgical procedures, including three craneotomies for resecting cerebral metastasis. More than four years of survival with good quality of life were obtained. An aggressive surgical therapy in the rare cases of cerebral metastasis of leiomyosarcoma may be justified.