Biomaterial Database

Covalent structure of biodegradative threonine dehydratase of Escherichia coli: homology with other dehydratases. 1987

P Datta, and T J Goss, and J R Omnaas, and R V Patil

The 987-base-pair coding region of the tdc gene of Escherichia coli K-12 encoding biodegradative threonine dehydratase [Tdc; L-threonine hydro-lyase (deaminating), EC 4.2.1.16], previously cloned in this laboratory, was sequenced. The deduced polypeptide consists of 329 amino acid residues with a calculated Mr of 35,238. Although the purified enzyme was shown to contain tryptophan, no tryptophan codon was found in the tdc reading frame. Incubation of purified Tdc with [14C]tryptophan revealed apparent "covalent" binding of tryptophan, indicating posttranslational modification of the enzyme. A heptapeptide, 54Thr-55Gly-56Ser-57Phe-58Lys-59Ile- 60Arg, was found to contain Lys-58, which binds pyridoxal phosphate coenzyme. A comparison of amino acid sequences between the Tdc polypeptide and the biosynthetic threonine dehydratases of yeast (encoded by ILV1) and E. coli (encoded by ilvA) and the E. coli D-serine dehydratase (DsdA, encoded by dsdA) revealed various extents of homology: five domains of the Tdc polypeptide were 63-93% homologous with the yeast enzyme, and three of these same regions were 80% homologous with the biosynthetic E. coli dehydratase; two different domains showed 67% and 83% homology with DsdA. In addition, two other sequences were highly conserved in all four proteins, one of which was shown to contain the conserved lysine residue that binds pyridoxal phosphate in the Tdc and DsdA polypeptides. These observations suggest that, despite their diverse origin and metabolic significance, these enzymes may have evolved from a common ancestral protein.

UI	MeSH Term	Description	Entries
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011732	Pyridoxal Phosphate	This is the active form of VITAMIN B 6 serving as a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. During transamination of amino acids, pyridoxal phosphate is transiently converted into pyridoxamine phosphate (PYRIDOXAMINE).	Pyridoxal 5-Phosphate,Pyridoxal-P,Phosphate, Pyridoxal,Pyridoxal 5 Phosphate,Pyridoxal P
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005796	Genes	A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.	Cistron,Gene,Genetic Materials,Cistrons,Genetic Material,Material, Genetic,Materials, Genetic
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial
D006836	Hydro-Lyases	Enzymes that catalyze the breakage of a carbon-oxygen bond leading to unsaturated products via the removal of water. EC 4.2.1.	Dehydratase,Dehydratases,Hydrase,Hydrases,Hydro Lyase,Hydro-Lyase,Hydro Lyases,Lyase, Hydro,Lyases, Hydro
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D012689	Sequence Homology, Nucleic Acid	The sequential correspondence of nucleotides in one nucleic acid molecule with those of another nucleic acid molecule. Sequence homology is an indication of the genetic relatedness of different organisms and gene function.	Base Sequence Homology,Homologous Sequences, Nucleic Acid,Homologs, Nucleic Acid Sequence,Homology, Base Sequence,Homology, Nucleic Acid Sequence,Nucleic Acid Sequence Homologs,Nucleic Acid Sequence Homology,Sequence Homology, Base,Base Sequence Homologies,Homologies, Base Sequence,Sequence Homologies, Base