ABSTRACT
In free-living and parasitic nematodes, the methylation of phosphoethanolamine to phosphocholine provides a key metabolite to sustain phospholipid biosynthesis for growth and development. Because the phosphoethanolamine methyltransferases (PMT) of nematodes are essential for normal growth and development, these enzymes are potential targets of inhibitor design. The pine wilt nematode (Bursaphelenchus xylophilus) causes extensive damage to trees used for lumber and paper in Asia. As a first step toward testing BxPMT1 as a potential nematicide target, we determined the 2.05 Å resolution x-ray crystal structure of the enzyme as a dead-end complex with phosphoethanolamine and S-adenosylhomocysteine. The three-dimensional structure of BxPMT1 served as a template for site-directed mutagenesis to probe the contribution of active site residues to catalysis and phosphoethanolamine binding using steady-state kinetic analysis. Biochemical analysis of the mutants identifies key residues on the ß1d-α6 loop (W123F, M126I, and Y127F) and ß1e-α7 loop (S155A, S160A, H170A, T178V, and Y180F) that form the phosphobase binding site and suggest that Tyr127 facilitates the methylation reaction in BxPMT1.
Subject(s)
Ethanolamines/chemistry , Helminth Proteins/chemistry , Methyltransferases/chemistry , Nematoda/enzymology , Pinus/parasitology , Plant Diseases/parasitology , Amino Acid Sequence , Animals , Binding Sites , Cloning, Molecular , Crystallography, X-Ray , Escherichia coli/genetics , Escherichia coli/metabolism , Ethanolamines/metabolism , Gene Expression , Genetic Vectors/chemistry , Genetic Vectors/metabolism , Helminth Proteins/genetics , Helminth Proteins/metabolism , Kinetics , Methyltransferases/genetics , Methyltransferases/metabolism , Models, Molecular , Nematoda/genetics , Protein Binding , Protein Conformation, alpha-Helical , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Substrate Specificity , ThermodynamicsABSTRACT
El cáncer representa un problema de salud pública. El cáncer de mama, es una entidad que aumenta su incidencia en el mundo. Esto ha llevado a nuevos enfoques terapéuticos quirúrgicos, químicos y radiantes. En el siguiente trabajo se hace mención del tratamiento con braquiterapia de alta tasa de dosis realizado en el Hospital Universitario de Mérida, en el servicio integral de oncología. Se evaluaron 148 pacientes con cáncer de mama en todos los estadios desde febrero 2007 hasta 30 mayo 2008. Se seleccionaron pacientes estadio I-IIANO MO, se analizaron las pacientes que reunieron los criterios de inclusión. En 19 pacientes (12,8 %) se cumplió braquiterapia intersticial hiperfraccionada con intervalo de 6 horas (800 cGy/día) 4 sesiones (400 cGy por fracción). Dosis total 3200 cGy. Con rango de seguimiento entre 18 meses y 2 meses y un promedio de 10 meses sin evidencia de recaída locorregional.
The breast cancer represents a public health problem. The breast cancer is entities which increase his incidence in the world. These problem do to a creation of new surgery, chemical and radiant therapeutically modes. In these work we mention the high dose brachytherapy tease doses realized in the University Merida Hospital in the integral service of oncology. We evaluated 148 patients with breast cancer disease in all the stage since February 2007 to May30 of 2008. We selected a 148 patients classified stage I-IIANO MO, and analyzed the patients with have inclusion therapeutically criterions. In 19 (12.8 %) patients were underwent to interstitial brachytherapy hyperfraccion with and interval to 6 hours (800 cGy/day) in 4 sessions (400 cGyfor fraction). Total doses applied was 3200 cGy. With a control range between 18 month and 2 month, and average of 10 month without any evidence of loco regional distress.
