Transcriptional Regulation and Posttranslational Activity of the Betaine Transporter BetL in Listeria monocytogenes Are Controlled by Environmental Salinity
AUTOR(ES)
Sleator, Roy D.
FONTE
American Society for Microbiology
RESUMO
While the genetic elements contributing to the salinity tolerance of Listeria monocytogenes have been well characterized, the regulatory signals and responses (genetic and/or biochemical) that govern these mechanisms have yet to be elucidated. Encoded by betL, the first genetic element to be linked to listerial osmotolerance, the secondary betaine uptake system BetL is a member of the betaine-carnitine-choline transporter family. Preceded by consensus σA- and σB-dependent promoter sites, betL is constitutively expressed and transcriptionally up-regulated in response to salt stress. The nisin-controlled expression system was used to achieve salinity-independent, controlled betL expression in Listeria. In the absence of NaCl-activated transcriptional control, BetL activity was found to be a function of environmental salinity, showing optimal activity in buffer supplemented with 1 to 2% NaCl (osmolality, 417 to 719 mosmol/kg). In addition, BetL was activated rapidly (half-life, 2 min) in response to an osmotic upshift imposed by adding 2% NaCl to 50 mM potassium phosphate buffer.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=296249Documentos Relacionados
- Identification and Disruption of BetL, a Secondary Glycine Betaine Transport System Linked to the Salt Tolerance of Listeria monocytogenes LO28
- Multiple Deletions of the Osmolyte Transporters BetL, Gbu, and OpuC of Listeria monocytogenes Affect Virulence and Growth at High Osmolarity
- Molecular and Physiological Analysis of the Role of Osmolyte Transporters BetL, Gbu, and OpuC in Growth of Listeria monocytogenes at Low Temperatures
- Betaine and L-carnitine transport by Listeria monocytogenes Scott A in response to osmotic signals.
- Regulation of Mannose Phosphotransferase System Permease and Virulence Gene Expression in Listeria monocytogenes by the EIItMan Transporter ▿