Carlos A. Iregui Castro

Análisis genómico al azar de Edwardsiella tarda ETSJ54: anotación de genes relacionados con virulencia

As an initial step to understand the pathogenic mechanisms displayed by Edwardsiella tarda during infection in fish, we conducted a random genome sequencing of cosmid and plasmid DNA libraries generated from a virulent E. tarda strain (ETSJ54) to identify putative virulence-related genes. The assumed virulence-related genes of E. tarda were grouped into nine categories including chemotaxis and motility, adhesion and invasion, endotoxin (LPS), toxin secretion by type I and type III secretion systems, iron uptake, proteases, and intra-macrophage survival. The results reveal that E. tarda is equipped with a wide range of genes involved in virulence and pathogenesis of diverse bacterial genera and species including Salmonella, Yersinia and Vibrios species. The results also indicate a high genetic flux in the E. tarda genome that could explain in some extent its potential to infect and to cause disease in a number of animal species.

Novel Synthesis of N -Glycosyl Amino Acids Using T3P ® : Propylphosphonic Acid Cyclic Anhydride as Coupling Reagent

In this paper is presented a novel and simple synthetic pathway for obtaining new protected and unprotected N-glucosyl amino acids from 2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl amine and Fmoc-l-amino acids. Three methodologies were evaluated, using the coupling reagents: N,N,N′,N′-Tetramethyl-O-(benzotriazol-1-yl)uronium tetrafluoroborate, diisopropylcarbodiimide and propylphosphonic acid cyclic anhydride. The obtained products using propylphosphonic acid cyclic anhydride showed less undesired species, easy purification and higher yields than the other two methodologies. Deprotection strategies widely used in solid phase peptide synthesis were applied to develop the synthetic pathway reported and achieve the final products. The protected and unprotected N-glucosyl amino acids were purified using solid phase extraction chromatography and characterized by high performance liquid Chromatography and nuclear magnetic resonance spectroscopy. Different amino acids (Fmoc-l-Asp(OtBu)OH, Fmoc-l-Phe(OH) and Fmoc-l-Lys(Boc)-OH) have been employed to demonstrate the simple and reproducible coupling methodology using propylphosphonic acid cyclic anhydride. The results showed that new protected and unprotected N-glucosyl amino acids can be obtained with high purity and the methodology could be used with any Fmoc-amino acid. The methodology developed could be considered as a synthetic tool for obtaining building blocks for glycopeptide synthesis and potential drugs candidates based on glycoconjugates.