Marcadores moleculares para la taxonomía e identificación del género Brucella (Alphaproteobacteria) / Molecular markers for the taxonomy and identification of the genus Brucella (Alphaproteobacteria)

Introducción: El género Brucella está incluido en la familia Brucellaceae que pertenece al orden Rhizobiales y es reconocido por su alto grado de patogenicidad. Las bacterias de este género son responsables de la brucelosis, enfermedad que ha sido reportada como una de las zoonosis más importantes a nivel mundial por su incidencia en el ganado y el hombre. Los estudios previos para la clasificación taxonómica del género, se han basado fundamentalmente en el análisis del gen 16S ARNr. Sin embargo, pocas investigaciones se han dirigido a la identificación de marcadores moleculares que distingan a sus miembros de otros grupos de bacterias. Objetivo: Identificar inserciones en secuencias de proteínas conservadas, que pudieran ser utilizados como marcadores moleculares para la taxonomía y diagnóstico de especies del género Brucella. Métodos: Las secuencias homólogas de las proteínas analizadas fueron obtenidas de bases de datos internacionales y, posteriormente, alineadas con el programa ClustalX2, para ello fueron considerados los parámetros sugeridos en la literatura. Resultados: Se identificaron inserciones en las proteínas oxoglutarato deshidrogenasa (componente E1) y ADN ligasa A específicas del género Brucella. Conclusiones: Las inserciones halladas pueden ser empleadas como complemento a los métodos tradicionales de clasificación taxonómica y para el diagnóstico molecular de bacterias incluidas en el género Brucella(AU)

Introduction: Brucella is a genus from the Brucellaceae family, Rhizobiales order. This genus is recognized for its high pathogenicity. Brucella bacteria cause brucellosis, a disease reported as one of the most important zoonoses worldwide due to its incidence in cattle and people. Previous studies on taxonomic classification of the genus have been mainly based on the analysis of gene 16S rDNA. However, few studies have been aimed at identification of molecular markers distinguishing its members from other groups of bacteria. Objective: Identify insertions in preserved protein sequences which could be used as molecular markers for the taxonomy and diagnosis of species from the Brucella genus. Methods: The homologous sequences for the proteins analyzed were obtained from international databases and aligned with the software ClustalX2, considering the parameters suggested in the literature. Results: Insertions were identified in the proteins oxoglutarate dehydrogenase (component E1) and DNA ligase A, specific of the genus Brucella. Conclusions: The insertions found may be used as complements to the traditional methods for taxonomic classification and for the molecular diagnosis of bacteria from the genus Brucella(AU)

Evolutionary placement of Xanthomonadales based on conserved protein signature sequences.

Xanthomonadales comprises one of the largest phytopathogenic bacterial groups, and is currently classified within the gamma-proteobacteria. However, the phylogenetic placement of this group is not clearly resolved, and the results of different studies contradict one another. In this work, the evolutionary position of Xanthomonadales was determined by analyzing the presence of shared insertions and deletions (INDELs) in highly conserved proteins. Several distinctive insertions found in most of the members of the gamma-proteobacteria are absent in Xanthomonadales and groups such as Legionelalles, Chromatiales, Methylococcales, Thiotrichales and Cardiobacteriales. These INDELs were most likely introduced after the branching of Xanthomonadales from most of the gamma-proteobacteria and provide evidence for the phylogenetic placement of the early gamma-proteobacteria. Moreover, other proteins contain insertions exclusive to the Xanthomonadales order, confirming that this is a monophyletic group and provide important specific genetic markers. Thus, the data presented clearly support the Xanthomonadales group as an independent subdivision, and constitute one of the deepest branching lineage within the gamma-proteobacteria clade.