Identification of two proline transport systems in Staphylococcus aureus and their possible roles in osmoregulation.
The food-borne pathogen Staphylococcus aureus is distinguished from other food-borne pathogens by its ability to grow at water activity values below 0.90. Previous studies have indicated that proline accumulation mediated by transport represents a primary osmoregulatory strategy utilized by this bacterium (C. B. Anderson and L. D. Witter, Appl. Environ, Microbiol. 43:1501-1503, 1982; I. Koujima, H. Hayashi, K. Tomochika, A. Okabe, and Y. Kanemasa, Appl. Environ. Microbiol. 35:467-470, 1978; K. J. Miller, S. C. Zelt, and J.-H. Bae, Curr. Microbiol. 23:131-137, 1991). In this study, we demonstrate the presence of two proline transport systems within whole cells of S. aureus, a high-affinity transport system (Km, 7 microM) and a low-affinity transport system (Km, 420 microM). Our results indicate that the low-affinity proline transport system is osmotically activated and is the primary system responsible for the accumulation of proline by this pathogen during growth at low water activity.
Bae
J H
JH
Department of Food Science, Pennsylvania State University, University Park 16802.
Miller
K J
KJ
D001622:Betaine / Q000378:metabolism; D001667:Binding, Competitive; D001692:Biological Transport / Q000187:drug effects; D007700:Kinetics; D011392:Proline / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000502:physiology*
D001622:Betaine; D012965:Sodium Chloride; D011392:Proline