Related Experiment Videos
The ascorbate transporter of Escherichia coli
Zhongge Zhang1, Mohammad Aboulwafa, Meghan H Smith
1Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116, USA.
Journal of Bacteriology
|March 20, 2003
Summary
Escherichia coli utilizes L-ascorbate anaerobically via the SgaTBA transporter system, which requires phosphotransferase system (PTS) proteins. This pathway involves specific uptake and phosphorylation of L-ascorbate.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- The phosphotransferase system (PTS) is crucial for nutrient uptake and metabolism in bacteria.
- L-ascorbate (Vitamin C) is an important metabolite with various biological roles.
- Understanding bacterial nutrient transport mechanisms is key to microbial physiology.
Purpose of the Study:
- To elucidate the genetic and biochemical basis of L-ascorbate utilization in Escherichia coli.
- To characterize the novel transporter system involved in L-ascorbate uptake and phosphorylation.
Main Methods:
- Genetic analysis of the sgaTBA gene cluster in Escherichia coli.
- In vitro biochemical assays for L-ascorbate phosphorylation.
- In vivo studies of L-ascorbate utilization under anaerobic conditions.
Main Results:
- The sgaTBA genes encode a novel L-ascorbate transporter (SgaT) and associated PTS proteins (SgaA, SgaB).
- Anaerobic L-ascorbate utilization requires SgaTBA, enzyme I, and HPr.
- The transporter exhibits high specificity and a low K(m) for L-ascorbate.
- Transcriptional regulation involves yjfQ, Crp, and Fnr; yjfR encodes a key lactonase.
Conclusions:
- SgaT represents a novel enzyme IIC, functioning with SgaA and SgaB in the L-ascorbate PTS pathway.
- This system facilitates phosphoryl transfer from HPr to L-ascorbate.
- The findings reveal a new mechanism for bacterial L-ascorbate metabolism.