Essential Role of Residue H49 for Activity of Escherichia coli 1-Deoxy--xylulose 5-Phosphate Synthase, the Enzyme Catalyzing the First Step of the 2-C-Methyl--erythritol 4-Phosphate Pathway for Isoprenoid Synthesis
- Resource Type
- Authors
- Santiago Imperial; Jordi Querol; Manuel Rodríguez-Concepción; Albert Boronat
- Source
- Biochemical and Biophysical Research Communications. 289:155-160
- Subject
- Molecular Sequence Data
Mutant
Biophysics
Saccharomyces cerevisiae
Transketolase
medicine.disease_cause
Biochemistry
Residue (chemistry)
Transferases
Catalytic Domain
Escherichia coli
medicine
Histidine
Polyisoprenyl Phosphate Sugars
Amino Acid Sequence
Molecular Biology
Peptide sequence
Conserved Sequence
DNA Primers
chemistry.chemical_classification
Base Sequence
Sequence Homology, Amino Acid
ATP synthase
biology
Cell Biology
Yeast
Erythritol
Enzyme
chemistry
Mutagenesis, Site-Directed
biology.protein
Sugar Phosphates
- Language
- ISSN
- 0006-291X
The first step of the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway for isoprenoid biosynthesis in plant plastids and most eubacteria is catalyzed by 1-deoxy-D-xylulose 5-phosphate synthase (DXS), a recently described transketolase-like enzyme. To identify key residues for DXS activity, we compared the amino acid sequence of Escherichia coli DXS with that of E. coli and yeast transketolase (TK). Alignment showed a previously undetected conserved region containing an invariant histidine residue that has been described to participate in proton transfer during TK catalysis. The possible role of the conserved residue in E. coli DXS (H49) was examined by site-directed mutagenesis. Replacement of this histidine residue with glutamine yielded a mutant DXS-H49Q enzyme that showed no detectable DXS activity. These findings are consistent with those obtained for yeast TK and demonstrate a key role of H49 for DXS activity.