Transport, Nutritional and Metabolic Studies of Taurine in Staphylococci

Abstract

A specific, Na+-dependent, energy-requiring transport system for taurine has been reported recently in the Staphylococcus aureus M strain. Taurine was taken up vigorously by all S . aureus strains tested. The system was Na+-dependent, and Na+ decreased the K , but had no effect on the V,,, of the transport system. Among coagulase-negative staphylococci, the Staphylococcus epidermidis group (a taxonomically related group of species associated with humans or other primates) and the free-living, wide-ranging species Staphylococcus sciuri showed vigorous taurine uptake. Somewhat lower rates were found in the Staphylococcus saprophyticus group. Low or barely detectable uptake rates were noted in other staphylococcal species that were primarily of animal origin. N o taurine uptake was detected in a variety of other bacterial species tested. Taurine uptake, which was not Na+-dependent, occurred in a Pseudomonas aeruginosa strain grown on taurine as sole energy, carbon, nitrogen, and sulphur source, but not when it was grown in a gluconate/salts medium. In nutritional studies we were unable to demonstrate a role for taurine as a sulphur source for S . aureus. [ 1 ,2-14C]-and [35S]taurine were taken up during overnight growth of cells, and radioactivity was distributed similarly among cellular fractions, indicating that the carbon and sulphur atoms of taurine were not cleaved and had the same fate.We were unable to demonstrate any catabolism of taurine in radiorespirometric experiments to detect evolution of I4CO2 by cells incubated with [ 1 ,2-14C]taurine. Thus, we found no evidence for a role of taurine in the energy, carbon and sulphur metabolism of S . aureus.

Control of Copper Resistance and Inorganic Sulfur Metabolism by Paralogous Regulators in Staphylococcus aureus

“…S. aureus does not encode a taurine repressor TauR; thus, taurine might also be indirectly sensed by CstR as sulfite or another metabolite (39). Taurine is a highly abundant amino acid in mammals and a dedicated Na ϩ -dependent uptake system for taurine is encoded by ssuBAC in S. aureus (35). However, S. aureus does not encode TauD or SsuDE and it is therefore unlikely that taurine is oxidized to aminoacetaldehyde with the release of sulfite.…”

“…Sulfite and alkylsulfonates, e.g. taurine, are likewise not assimilated and sulfite cannot be metabolized (35,36). Organic sulfur sources, including glutathione and homocysteine, are preferred sources of cysteine, but both must be acquired by S. aureus from the host.…”

“…Two cysteine residues on opposite subunits within a dimer make coordination bonds to the Cu(I) ion, with the third ligand a His from the ␣2 helix (Cys 36 Ј, His 61 , Cys 65 ), thus completing a trigonal S 2 N coordination complex (13). Additionally, two conserved second coordination shell residues, Tyr 35 Ј and Glu 81 , play critical roles in driving allosteric negative regulation of DNA binding by Cu(I) within the tetramer (15,16).…”

Staphylococcus aureus osmoregulation: roles for choline, glycine betaine, proline, and taurine

“…In this laboratory, studies of staphylococcal methicillin resistance (24) and the discovery of a unique, highly specific, Na+-dependent transport system for taurine in staphylococci (2,11,36) were two lines of investigation that led to the present study of staphylococcal osmoregulation.…”

“…When sucrose was used to adjust medium osmolarity, it was filter sterilized. The basic defined medium was that of Giehl et al (11), which was based upon that of Pattee and Neveln (31), with the proline content lowered to 20 ,uM. A modified defined medium, referred to as lOx defined medium, was also used in some studies because of relatively poor growth in the defined medium under high levels of osmotic stress.…”