Characterization of Glycine Betaine Porter I from Listeria monocytogenes and Its Roles in Salt and Chill Tolerance
AUTOR(ES)
Mendum, Mary Lou
FONTE
American Society for Microbiology
RESUMO
Listeria monocytogenes is a pathogenic bacterium that can grow at low temperatures and elevated osmolarity. The organism survives these stresses by the intracellular accumulation of osmolytes: low-molecular-weight organic compounds which exert a counterbalancing force. The primary osmolyte in L. monocytogenes is glycine betaine, which is accumulated from the environment via two transport systems: glycine betaine porter I, an Na+-glycine betaine symporter; and glycine betaine porter II, an ATP-dependent transporter. The biochemical characteristics of glycine betaine porter I were investigated in a mutant strain (LTG59) lacking the ATP-dependent transporter. At 4% NaCl, glycine betaine uptake in LTG59 was about fivefold lower than in strain DP-L1044, which has both transporters, indicating that the ATP-dependent transporter is the primary means by which glycine betaine enters the cell. In the absence of osmotic stress, cold-activated uptake by both transporters was most rapid between 7 and 12°C, but a larger fraction of the total uptake was via the ATP-dependent transporter than was observed under salt-stressed conditions. Twelve glycine betaine analogs were tested for their ability to inhibit glycine betaine uptake and growth of stressed cultures. Carnitine, dimethylglycine, and γ-butyrobetaine appear to inhibit the ATP-dependent transporter, while trigonelline and triethylglycine primarily inhibit glycine betaine porter I. Triethylglycine was also able to retard the growth of osmotically stressed L. monocytogenes grown in the presence of glycine betaine.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=126668Documentos Relacionados
- Osmotic and Chill Activation of Glycine Betaine Porter II in Listeria monocytogenes Membrane Vesicles
- Gbu Glycine Betaine Porter and Carnitine Uptake in Osmotically Stressed Listeria monocytogenes Cells
- Role of the Glycine Betaine and Carnitine Transporters in Adaptation of Listeria monocytogenes to Chill Stress in Defined Medium
- Identification and Disruption of BetL, a Secondary Glycine Betaine Transport System Linked to the Salt Tolerance of Listeria monocytogenes LO28
- Glycine betaine confers enhanced osmotolerance and cryotolerance on Listeria monocytogenes.