Metabolic Reactions of Pasteurella Pestis

Abstract

indicated that the hexose monophosphate shunt is of little quantitative significance in the anaerobic dissimilation of glucose by nonproliferating, resting cells of PasteureUa petis. However, the observations that dried celLs metabolized gluconate and that cell-free extracts converted glucose-6-phosphate to a pentose phosphate suggesd that the shunt pathway may be involved in some way in the overall metabolism of P. pestis. Since Cohen (1951) suggested that the primary function of the hexose monophosphate shunt is to supply pentose phosphates for synthetic reactions, it was of interest to determine whether this alternate pathway is involved in the growth of this bacterium. The results of such experiments are described in this report. METHODS The methodology and experimental manipulations employed in this investigation were analogous to those previously described (Santer and Ajl, 1955). For the preparation of cell-free extracts, P. pesti strin Tjiwidej was grown for 24 hours on a trypticase soy broth medium at room temperature with constant aeration. After centrifugation the cells were ground with "alumina 303" according to the procedure described by McIlwain (1948). Growth experiments with 1-C'4-glucose were performed in Warburg vesels at 33 C. A standardized inoculum of P. pestis was introduced into 2.3 ml of growth medium made up to contain 3 per cent trypticase soy broth and a known quantity of radioactive glucose. Growth was

Antigenic and phenotypic modifications of Yersinia pestis under calcium and glucose concentrations simulating the mammalian bloodstream environment

“…In contrast, addition of glucose alone in HB with no added calcium, i.e. to 'resting' cells (not stimulated by calcium), when it can be fermented almost exclusively via the Embden-Meyerhof scheme (Santer & Ajl, 1955), resulted in a weak increase in bacterial yield.…”

“…Apparently, calciumspecific ion channels of the Y. pestis bacterial membrane open in media containing calcium in concentrations similar to that in the mammalian bloodstream environment (Metzler, 1980), resulting in the influx of calcium from extracellular sources into the bacterial cells and then, via some consequent cascade reactions, stimulation of DNA biosynthesis and bacterial proliferation (Janeway & Travers, 1997). Glucose is reported to be the main carbohydrate source for actively growing Y. pestis cells because only in its presence do both the Embden-Meyerhof scheme and the hexose monophosphate shunt pathway operate (Santer & Ajl, 1955). Indeed, uptake of glucose by Y. pestis occurred more effectively when it was added to the media in combination with calcium, which obviously stimulated the bacterial growth, i.e.…”

“…The data obtained support the hypothesis that an adequate concentration of calcium in the mammalian bloodstream initiates the operation of an alternative pathway of dissimilation of glucose, enabling effective multiplication of Y. pestis in vivo at the extracellular stage. It is likely that these observations are correlated with the mutation in the gene encoding a glucose-6-phosphate dehydrogenase (Brubaker, 2000), the main enzyme of the pathway, during the divergence of Y. pestis from Yersinia pseudotuberculosis, resulting in the production of only two isoforms of glucose-6phosphate dehydrogenase by Y. pestis, in contrast to three in Y. pseudotuberculosis (Kouzmitchenko & Naumov, 1989), and in small or undetectable amounts of this enzyme in routine media (Brubaker, 2000;Kouzmitchenko & Naumov, 1989;Santer & Ajl, 1955). Strong evidence for Y. pestis retaining production of the enzyme in this case was the presence of the enzyme intracellularly in dried bacterial cells (Kouzmitchenko & Naumov, 1989;Santer & Ajl, 1955).…”

“…It is likely that these observations are correlated with the mutation in the gene encoding a glucose-6-phosphate dehydrogenase (Brubaker, 2000), the main enzyme of the pathway, during the divergence of Y. pestis from Yersinia pseudotuberculosis, resulting in the production of only two isoforms of glucose-6phosphate dehydrogenase by Y. pestis, in contrast to three in Y. pseudotuberculosis (Kouzmitchenko & Naumov, 1989), and in small or undetectable amounts of this enzyme in routine media (Brubaker, 2000;Kouzmitchenko & Naumov, 1989;Santer & Ajl, 1955). Strong evidence for Y. pestis retaining production of the enzyme in this case was the presence of the enzyme intracellularly in dried bacterial cells (Kouzmitchenko & Naumov, 1989;Santer & Ajl, 1955). We believe that this reflects adaptation of Y. pestis to the bloodstream environment abundant in glucose because a direct correlation between active metabolism of the enzyme and the development of resistance to phagocytosis has been found (Burrows & Bacon, 1956a).…”

Coregulation of host-adapted metabolism and virulence by pathogenic yersiniae

“…They possess a complex metabolic system with a full complement of often redundant or alternative catabolic and biosynthetic pathways that render them very flexible and robust against changing nutrient concentrations and genetic manipulations. Early studies revealed that all pathogenic yersiniae are able to catabolize glucose by the Emden–Meyerhof and Entner–Doudoroff pathway with a complete tricarboxylic acid (TCA) cycle and a functional glyoxylate bypass (Santer and Ajl, 1955 ; Mortlock, 1962 ; Brubaker, 1968 ; Motin et al, 2004 ). However, in contrast to the enteropathogenic Yersinia species, the glyoxylate shunt is constitutive in Y. pestis .…”