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

Abstract

Choline, glycine betaine, and L-proline enhanced the growth of Staphylococcus aureus at high osmolarity (i.e., they acted as osmoprotectants) on various liquid and solid defined media, while an osmoprotective effect of taurine was shown only for cells growing on high-NaCl solid medium that lacked other osmoprotectants. Potassium pool levels were high, and there was little difference in levels in cells grown at different osmolarities. Glycine betaine accumulated to high levels in osmotically stressed cells, and choline was converted to glycine betaine. Proline and taurine also accumulated in response to osmotic stress but to lower levels than glycine betaine.

Synthesis of the osmoprotectant glycine betaine in Bacillus subtilis: characterization of the gbsAB genes

“…This phenomenon is probably connected with the maintenance of the very high turgor found in B. subtilis (55). The maintenance of high turgor would most likely favor the accumulation of osmotically active solutes compatible with the normal functioning of the cell instead of ionic osmolytes which are deleterious at high concentrations (4,15,29). The presence of 1 mM choline or glycine betaine aldehyde in a minimal medium with 0.4 M NaCl has little effect on the growth of the gbsAB ϩ wild-type strain JH642 but strongly impairs the growth of the gbsAB mutant JBB5 (Fig.…”

“…In contrast, the systems mediating the enzymatic conversion of choline into glycine betaine are only marginally stimulated by an increase in medium osmolarity (4). B. subtilis shares the ability to oxidize choline to glycine betaine for osmoprotective purposes with a number of gram-negative and gram-positive bacteria (8,15,35). This process has been most intensively studied at both the molecular and biochemical levels for E. coli (30,31).…”

Proline is biosynthesized from arginine in Staphylococcus aureus

“…The intracellular amino acid pools of strain 8325 grown with different concentrations of arginine and glutamate were measured in late exponential phase cells. The pool metabolites fraction was obtained by trichloroacetic acid extraction as described by Christian (1961) and Graham & Wilkinson (1992). Amino acid analysis by HPLC of phenylisothiocyanate derivatives was performed on a Waters P I C 0 TAG column according to the method of Bildingmeyer e t al.…”

Glycine betaine transport by Staphylococcus aureus: evidence for two transport systems and for their possible roles in osmoregulation

“…aureus can accumulate proline in response to osmotic stress has been established (Koujima et al, 1978 ; Anderson & Witter, 1982). The stimulation of transport activity rather than de novo synthesis of the amino acid was reported to be responsible for the five-fold change in the proline pool of this organism after an increase in the external osmolarity (Koujima et al, 1978 shown that glycine betaine can also be accumulated to high levels (Miller et al, 1991;Graham & Wilkinson, 1992). In defined medium, betaine was shown to be more effective than proline in enhancing the growth of cells in the presence of 15% (w/v) NaCl (Miller et al, 1991 ;Graham & Wilkinson, 1992).…”

“…The stimulation of transport activity rather than de novo synthesis of the amino acid was reported to be responsible for the five-fold change in the proline pool of this organism after an increase in the external osmolarity (Koujima et al, 1978 shown that glycine betaine can also be accumulated to high levels (Miller et al, 1991;Graham & Wilkinson, 1992). In defined medium, betaine was shown to be more effective than proline in enhancing the growth of cells in the presence of 15% (w/v) NaCl (Miller et al, 1991 ;Graham & Wilkinson, 1992). Subsequently, it was shown that there are two proline transport systems in S. aureus: a high-affinity system insensitive to osmotic stress, and a low-affinity transport system activated by osmotic stress (Bae & Miller, 1992;Townsend & Wilkinson, 1992).…”