RESUMEN
A gene encoding phosphatidyl inositol-4,5-bisphosphate phospholipase C (PLC) was cloned from the protozoan parasite Trypanosoma cruzi. A partial cDNA encoding putative PLC was obtained by a polymerase chain reaction (PCR) using degenerate oligonucleotide primers corresponding to conserved regions of PLCs. A 2178-bp protein coding region of the T. cruzi PLC gene, composed from cDNA and genomic clones, encodes a putative PLC with a calculated molecular mass of 82,032 Da and an isoelectric point of 5.93. The deduced amino acid sequence of T. cruzi PLC exhibited 23-42% overall identities with the PLCs from other organisms. Among them, PLC from Ictalurus punctatus revealed the highest identity to T. cruzi PLC. The percentage identities of the entire proteins and the catalytic X/Y domains suggested that T. cruzi PLC is more evolutionarily related to the PLCs of higher eukaryotes than to those of lower unicellular eukaryotes. The tetrad analysis of the segregants of the Saccharomyces cerevisiae PLC1/plc1::HIS3 diploid strain transformed with the T. cruzi PLC-expressing plasmid showed that expression of T. cruzi PLC suppressed the growth defect caused by the plc1 disruption in yeasts. Temperature-sensitive phenotype of the S. cerevisiae plc1-mutant haploid strain was also suppressed by the expression of T. cruzi PLC. The phosphatidyl inositol-4,5-biphosphate (PtdIns(4,5)P2) hydrolyzing activity of T. cruzi PLC was demonstrated in the lysate from the plc1-temperature sensitive yeast mutant strain transformed with the T. cruzi PLC-expressing plasmid. The yeast-expressed T. cruzi PLC showed an absolute Ca2+ dependence which was similar to mammalian PLC isoforms: the half-maximal activity at 0.5-1 x 10(-5) M Ca2+ and the maximal activity at 1-2 x 10(-4) M Ca2+.
Asunto(s)
Clonación Molecular , Genes Protozoarios , Trypanosoma cruzi/enzimología , Fosfolipasas de Tipo C/genética , Secuencia de Aminoácidos , Animales , Southern Blotting , Cartilla de ADN , ADN Complementario/genética , Prueba de Complementación Genética , Datos de Secuencia Molecular , Fosfatidilinositol 4,5-Difosfato/metabolismo , Fosfatidilinositol Diacilglicerol-Liasa , Reacción en Cadena de la Polimerasa/métodos , Alineación de Secuencia , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Transducción de Señal , Trypanosoma cruzi/genética , Fosfolipasas de Tipo C/química , Fosfolipasas de Tipo C/metabolismo , Levaduras/enzimología , Levaduras/genéticaRESUMEN
Liver abscess is a rare complication of Crohn's disease and in most of the reported cases, the diagnosis of Crohn's disease preceded that of liver abscess. We report herein a case in which a liver abscess was the initial clinical manifestation of Crohn's disease in a 36 year old man who presented with high fever and weakness. The diagnosis of liver abscess was established by abdominal ultrasonography, computed tomography and an arterial blood culture. The abscess was resolved with antibiotic therapy alone and during the drug therapy, a barium enema examination was performed which revealed a stricture at the transverse colon. Resection of the transverse colon was performed and macroscopic and microscopic examination of the resected specimen established the diagnosis of Crohn's disease. The liver abscess was thus speculated to be secondary to the inflamed bowel. Although rare, Crohn's disease should be included in the differential diagnosis of diseases causing liver abscess.