REGULATION OF SUGAR TRANSPORT AND METABOLISM IN LACTIC ACID AND ORAL BACTERIA

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This project concentrates on a basic science research program emphasizing the physiology, biochemistry, and genetic basis of regulation of amino acid and sugar fermentation pathways of oral bacteria. This fundamental knowledge is essential for identification of the causes, as well as, formulation of treatments and prevention of oral diseases. The following accomplishments have been made during this period: 1. Two enzymes: (a) sucrose 6-phosphate hydrolase, and (b) ATP- dependent fructokinase, are required for sucrose fermentation by Fusobacterium mortiferum. These two enzymes have been purified to electrophoretic homogeneity. The physicochemical properties, catalytic functions and N-terminal amino acid sequences of the proteins have been established. 2. The roles(s) of sulfur-transducing enzymes in pathogenicity of Fusobacteria are being defined. One of the enzymes, cystathionase, has been partially purified from F. mortiferum. 3. The mechanism of toxicity of extracts of Bordetella avium toward mammalian osteoblast cells has been delineated, and attributed to the desulfuration of L-cystine by beta-cystathionase. This enzyme has been purified to homogeneity, and the gene (met c) has been cloned and sequenced. 4. The cloning, expression and sequencing of the gene encoding N(5)- (carboxyethyl) ornithine synthase from Lactococcus lactis have been accomplished. 5. Two new N-(carboxyalkyl) amino acids have been synthesized via enzyme catalyzed reactions mediated by N(5)-(CE)ornithine synthase. N(5)-(Carboxymethyl) ornithine and N(6)-(carboxymethyl) lysine have been purified, and characterized by 1H,13C-NMR and GC-mass spectroscopy. 6. The results of the preceding investigations have been presented, and discussed in six peer-reviewed publications.