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The degree of substitution of Desulfovibrio desulfuricans lipopolysaccharides and their lipid A component by phosphates |
| Jolanta Lodowska 1, Marzena Jaworska-Kik 2, Daniel Wolny 2, Zofia Dzierżewicz 2, Ludmiła Węglarz 1 |
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1. Department of Biochemistry, Medical University of Silesia, Narcyzów 1, Sosnowiec 41-200, Poland |
| Abstract |
Bacteria of the Desulfovibrio desulfuricans species are Gram-negative, anaerobic, sulphate – reducing rods that settle various ecosystems including human digestive track. These bacteria are suggested to be involved in the pathogenesis of some colon disorders such as ulcerative colitis or Crohn disease. Endotoxin (lipopolysaccharide, LPS) is the integral component of bacterium cell outer membrane and a factor responsible for the virulence of D. desulfuricans bacteria. The biological activity of LPS is determined by its chemical structure, including the degree of lipid A saccharide hydroxyl groups substitution by phosphates. The less lipid A is substituted by phosphates the less active it is. The aim of the study was to establish the degree of substitution of endotoxin and lipid A, derived from D. desulfuricans, by phosphates. The standard soil strain La2226 and the wild strains (DV/A, DV/B, DV/H, DV/I, DV/I/1) of D. desulfovibrio have been used. The strains have been cultured for 10 days on pyruvate Postgate medium (30ºC, pH 7.5) at anaerobic conditions (80% N2, 10% H2, 10% CO2) [3]. LPS was isolated from a biomass by water-phenol extraction according to the Westphal et al. method [4]. The quantity of phosphorus in LPS and in lipid A, liberated from LPS by mild acid hydrolysis, was established by the Bartlett method [1]. The results of spectrophotometrical analysis showed the interstrain differences in phosphorus content in both LPS and lipid A of D. desulfovibrio. This could result from not only different level of LPS and lipid A phosphorylation but also from variations in the average molecular mass of these heteropolymers. LPS extracted from a particular bacterial strains is not structurally homogenous and rather, it consists of a group of molecules differing in molecular mass, structural details and physicochemical properties. Smaller quantities of phosphorus in LPS suggest the greater quantitative contribution of sugar component to endotoxin structure. Previous studies by Dzierżewicz et al. [2] revealed macromolecular differentiation of endotoxins from DV/A and La2226 isolates indicating that the intestinal wild strain is characteristic of a greater content of LPS molecules containing more complex polysaccharide fragment and therefore of the greater molecular mass than the soil strain. The interesting finding of our study was also related to the different phosphorus quantity in LPS derived from DV/I and DV/I/1 strains isolated from the feces and biopsy specimen, respectively, of the same patient. References [1] Bartlett G.R., J. Biol. Chem. 1959; 234(3): 466-468 [2] Dzierżewicz Z., Orchel A., Komarska-Szostak A., Wawszczyk J., Węglarz L., Szczerba J., Wilczok T. Ann. Acad. Med. Siles. 2005; 59: 9-16 [3] Postgate JR., The sulphate-reducing bacteria. Cambridge University Press. Cambrige 1984 [4] Westphal O., Luderitz O., Bister F. Z. Naturforsch. 1952, 78: 148-155 |
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Presentation: Poster at Zjazd Polskiego Towarzystwa Biochemicznego, Sympozjum D, by Zofia DzierżewiczSee On-line Journal of Zjazd Polskiego Towarzystwa Biochemicznego Submitted: 2007-04-26 12:50 Revised: 2009-06-07 00:44 |