Distribution of surface-exposed antigenic glycolipids in recent clinical isolates of Mycobacterium tuberculosis

The distribution of surface-exposed antigenic glycolipids in seven recent clinical isolates of Mycobacterium tuberculosis was established. Thin- layer and liquid chromatographies revealed a uniformity in the glycolipid pattern. Chemical analysis of the individual glycolipids of a selected strain enabled the identification of glycolipids of serological interest in all the other clinical isolates. Phenolic glycolipid-Tb1 (PGL-Tb1) was lacking in all strains, but appreciable amounts of a partially deglycosylated version (PGL- Tb1D) were present in the seven isolates. Diacyltrehaloses (DATs) were detected in all strains, showing themselves to be major glycolipids. Lipooligosaccharides (LOS-II) were present in the seven strains studied though only in trace amounts. These results shed new light on the open debate on the distribution of these interesting glycolipids in typical clinical isolates of M. tuberculosis. In the search for a serological test for tuberculosis, and in accordance with our observations, we believe that PGL- Tb1 and LOS-II should not be the target molecules for serology and that it is worthwhile to continue investigating the value of DATa as antigens. We also believe that it would be of interest to undertake research to assess the usefulness of PGL-Tb1D as an antigen.link_to_subscribed_fulltex

Components and Key Regulatory Steps of Lipid Biosynthesis in Actinomycetes

The biochemical steps in fatty acid synthesis are highly conserved in bacteria andin most organisms. However, the data provided by the massive genomic sequencingrevealed a surprising amount of diversity in the genes, enzymes, and geneticorganization of the components responsible for bacterial lipid synthesis, withthese differences being even more striking in the order Actinomycetales. Fattyacid biosynthesis is energetically very expensive for the cell; therefore, adjustingthe rate of fatty acid synthesis, in order to maintain membrane lipid homeostasis,is a key factor for bacterial survival. Bacteria have evolved sophisticated anddiverse mechanisms to finely control the expression of the genes responsible forthe synthesis of fatty acids and, in some cases, also by regulating the activity ofthe pacemaker enzymes. In this chapter we summarize the main components offatty acid biosynthesis and their regulation in different genera of actinomycetes,highlighting the main differences found between them and also with otherbacteria. The main focus has been put into the acyl-CoA carboxylases, the fattyacid synthases, and on the regulatory elements that control these pathways.Fil: Gago, Gabriela Marisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Arabolaza, Ana Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Diacovich, Lautaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gramajo, Hugo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentin