Abstracts » Biological sciences

Proline is biosynthesized from arginine in Staphylococcus aureus

Article Abstract:

Proline is biosynthesized from arginine through the ornithine and delta'-pyrroline 5-carboxylate pathway in Staphylococcus aureus rather than from the glutamate pathway. Strain 8325 shows a long lag phase when grown in a medium without proline, but addition of arginine shortens the lag phase. Radioactivity from L-(14C)arginine is incorporated into a spot where the chromatographic mobility corresponds to that of (14C)proline. Radioactivity from L-(14C)glutamate fails to be incorporated. Mutants auxotrophic for proline grow in the presence of arginine as the carbon and energy source.

Mutation (Biology), Mutation, Amino acids, Amino acid synthesis

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Characterization of a chromosomally encoded glycylglycine endopeptidase of Staphylococcus aureus

Article Abstract:

The lytM gene, a lytic-enzyme-encoding gene, may be a member of the zinc protease family as indicated by a homologous 38-amino-acid motif, Tyr-X-His-X(sub 11)-Val-X(sub 12/20)-Gly-X(sub 5-6)-His. This was gleaned from an experiment in which the gene was overexpressed in Escherichia coli and then purified to homogeneity by affinity chromatography and high performance liquid chromatography. Moreover, it is possible that lytM plays a role in cell growth since a uniform distribution of gold particles was found on the surface of actively growing bacterial cells.

Proteases, Gene expression, Glycine, Genetic code, Chromosomal proteins

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Characterization of an NaCl-sensitive Staphylococcus aureus mutant and rescue of the NaCl-sensitive phenotype by glycine betaine but not by other compatible solutes

Article Abstract:

Staphylococcus aureus NaCl-sensitive mutants exhibiting Tn917-lacZ insertions were analyzed by Southern blotting to determine the osmoregulatory mechanisms of the pathogenic microbe. The Staphylococcus aureus mutants with Tn917-induced NaCl-sensitivity exhibited high levels of L-[14C]proline and [14C]glycine betaine uptake under hyperosmotic stress. The levels of K+, proline and glycine betaine uptake were also similar between wild-type and mutant strains. However, the production of NaCl stress proteins was impaired by the presence of glycine betaine.

Fluid-electrolyte balance, Osmoregulation, Salt, Salt (Food)

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