The Ascorbate Transporter of Escherichia coli
Open Access
- 1 April 2003
- journal article
- research article
- Published by American Society for Microbiology in Journal of Bacteriology
- Vol. 185 (7) , 2243-2250
- https://doi.org/10.1128/jb.185.7.2243-2250.2003
Abstract
The sgaTBA genes of Escherichia coli encode a putative 12-transmembrane α-helical segment (12 TMS) transporter, an enzyme IIB-like protein and an enzyme IIA-like protein of the phosphotransferase system (PTS), respectively. We show that all three proteins as well as the energy-coupling PTS proteins, enzyme I and HPr, are required for the anaerobic utilization and uptake of l -ascorbate in vivo and its phosphoenolpyruvate-dependent phosphorylation in vitro. The transporter exhibits an apparent
K
m
for l -ascorbate of 9 μM and is highly specific. The sgaTBA genes are regulated at the transcriptional level by the yjfQ gene product, as well as by Crp and Fnr. The yjfR gene product is essential for l -ascorbate utilization and probably encodes a cytoplasmic l -ascorbate 6-phosphate lactonase. We conclude that SgaT represents a novel prototypical enzyme IIC that functions with SgaA and SgaB to allow phosphoryl transfer from HPr(his-P) to l -ascorbate via the phosphoryl transfer pathway: PEP → enzyme I-P → HPr-P → IIA- \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \(\stackrel{\mathrm{SgaA}}{\mathrm{P}}\) → IIB- \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \(\stackrel{\mathrm{SgaB}}{\mathrm{P}}\) \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \(\stackrel{\textstyle{\mathrm{IIC^{SgaT}}}}{{\rightarrow}}\) l -ascorbate-6-P.
Keywords
This publication has 40 references indexed in Scilit:
- Nitric oxide regulates bacterial translocation in experimental acute edematous pancreatitisPancreatology, 2003
- The Gene yjfQ Encodes the Repressor of the yjfR-X Regulon ( ula ), Which Is Involved in l -Ascorbate Metabolism in Escherichia coliJournal of Bacteriology, 2002
- Sites Important for Na+ and Substrate Binding in the Na+/Proline Transporter of Escherichia coli, a Member of the Na+/Solute Symporter FamilyPublished by Elsevier ,2002
- Homologous (β/α)8-Barrel Enzymes That Catalyze Unrelated Reactions: Orotidine 5‘-Monophosphate Decarboxylase and 3-Keto-l-Gulonate 6-Phosphate Decarboxylase,Biochemistry, 2002
- Utilization of l -Ascorbate by Escherichia coli K-12: Assignments of Functions to Products of the yjf-sga and yia-sgb OperonsJournal of Bacteriology, 2002
- Genes Involved in Control of Galactose Uptake in Lactobacillus brevis and Reconstitution of the Regulatory System in Bacillus subtilisJournal of Bacteriology, 2001
- Pathway engineering for the production of aromatic compounds in Escherichia coliNature Biotechnology, 1996
- Novel Phosphotransferase System Genes Revealed by Bacterial Genome Analysis: Operons Encoding Homologues of Sugar-Specific Permease Domains of the Phosphotransferase System and Pentose Catabolic EnzymesGenome Science and Technology, 1996
- The bacterial phosphotransferase system: new frontiers 30 years laterMolecular Microbiology, 1994
- Effect of ascorbate on oxygen uptake and growth of Escherichia coli BCanadian Journal of Microbiology, 1988