Survey of Taurine Uptake and Metabolism in Staphylococcus aureus

Abstract

Taurine has been reported to be a component of the capsular polysaccharide of the encapsulated M strain of Staphylococcus aureus. This led to a study of the uptake and metabolism of [ 1,2-4C]taurine in a variety of encapsulated and unencapsulated S. aureus strains. Taurine was taken up by all strains studied. A discrepancy between uptake measured as depletion of radioactivity from growth medium and as cell-associated radioactivity suggested that taurine may be catabolized to CO, in some strains. In most strains, cell-associated radioactivity was located mainly in cold TCA-soluble (pool metabolites) fractions. About 90% of the cellassociated radioactivity was present in the pool metabolites fraction in the M strain, and about 10 % in hot TCA-soluble (nucleic acid-teichoic acid-capsular polysaccharide) fraction.Radioactivity in spent medium and the capsular polysaccharide-containing fraction appeared to be present as taurine in this strain. Radioactivity in the pool metabolites fraction of three of the strains examined did not chromatograph as taurine, indicating that taurine was converted into other cell metabolites. One strain incorporated radioactivity from taurine into cellular macromolecules, thus revealing a heterogeneity of staphylococcal taurine metabolism.

Transport, Nutritional and Metabolic Studies of Taurine in Staphylococci

“…We attempted to observe any stimulatory effect taurine might have on growth, and focussed on whether taurine could serve as a sulphur source for staphylococci (Smiley & Wilkinson, 1983). In most experiments glucose served as the major carbon source and sulphur was supplied in the form of (NH,)?SO,, cystine and methionine, and in minor amounts in the form of the vitamins thiamin and biotin.…”

“…In previous studies this strain had shown the largest discrepancy in taurine uptake measured by disappearance versus cell-associated radioactivity (Smiley & 2 2 4 1 4 1 0 4 4 3 2 6 Nucleic acid-teichoic acid-capsular polysacc haride < 1 3 < 1 < 1 8 12 < 1 5 < 1 < I 14 36 Protein < 1 < 1 < I < I < 1 < 1 < I < 1 < 1 < I < I < I Peptidogl ycan < 1 < 1 < I < 1 2 2 < 1 2 < 1 < 1 7 2 * Percentage of total radioactivity supplied taken up by cells calculated by difference between uninoculated and t The starting radioactivity in harvested cells (100%) was los-lo6 c.p.m. spent medium or by direct counting of cells (Smiley & Wilkinson, 1983). 1983). Substantial oxygen uptake was observed when glucose was supplied as a substrate (data not shown).…”

“…Later, it was shown that a variety of Staph. aureus strains took up radiolabelled taurine from the growth medium during overnight growth, and appeared to carry out some limited metabolism of taurine (Smiley & Wilkinson, 1983). This led to the discovery of an Na+-dependent, energy-requiring, highly specific uptake system for taurine in the M strain (Bieber & Wilkinson, 1984).…”

“…Growth was measured by determining the ODss0 of 1 : 10 diluted samples in a Spectronic 20 spectrophotometer (Bausch & Lomb). ['"CJ-and (Smiley & Wilkinson, 1983) and defined medium (25 ml per 50 ml Erlenmeyer flask). Unlabelled taurine was supplied at 0.1 mM and 1 pCi radiolabelled taurine was added.…”

“…Unlabelled taurine was supplied at 0.1 mM and 1 pCi radiolabelled taurine was added. Uptake and distribution of radioactivity among cellular fractions were determined as described by Smiley & Wilkinson (1983). Respirometry.…”