The outer leaflet of the outer membrane of the gram-negative bacterial cell envelope is built of lipopolysaccharide (LPS). The LPS consists of three distinct structural regions; a rather conserved lipid A, a more variable core oligosaccharide (OS), and an even more variable O-antigen polysaccharide (OPS). These regions are known to play important roles in interacting with the defense mechanisms of the host cells. In addition LPS, as well as capsular polysaccharides (CPS) and bacterial extracellular polysaccharides (EPS) are essential for protecting bacteria from environmental stress and in symbiotic interactions.
Determination of chemical and structural properties of these glycan and glycolipid macromolecules is critical in understanding the mechanisms of the host-microbe interactions and, in the case of pathogenic bacteria, in searching for good vaccine candidates. Through past years of my work I was involved in studies on LPS or lipid A from pathogenic, Pseudomonas aeruginosa, Neisseria meningitidis, Neisseria gonorrhoeae, Francisella novicida, Fancisella tularensis, Moraxella catharrhalis, Yersinia pestis, Yersinia enterocolitica, Bulkholderia multivorans, Helicobacter pylori, Campylobacter jejuni, Xyllela fastidiosa, Rimerella antipestifer, Granulibacter bethesdensis and nitrogen fixing Rhizobium leguminosarum, Rhizobium galegae, Sinorhizobium meliloti, Rhizobium etli, Mesorhizobium loti, Herbaspirillum seropedicae, and on peptidoglycan in Micrococcus lutes and Neisseria sp.
My current research projects involve studies on structural and biological properties of Mesorhizobium loti EPS, roles of polysaccharides in biofilm formation, in pathogenic Campylobacter jejuni and Helicobacter pylori, and biochemical studies on lipopolysaccharide of Bradyrhizobium japonicum and its role in legume symbiosis.
These studies utilize various techniques used in biochemistry and microbiology laboratories and analytical techniques, particularly chromatography and mass spectrometry (GPC, GLC-MS, CI-MS, HPLC, TLC, ESI-MS, MALDI-TOF and TOF-TOF MS) and NMR spectroscopy.