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Three-dimensional structure of tyrosine phenol-lyase
A A Antson1, T V Demidkina, P Gollnick
1Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow.
Biochemistry
|April 27, 1993
Summary
Tyrosine phenol-lyase from Citrobacter freundii was cloned and its structure determined. Key residues and structural similarities to aminotransferases were identified, revealing the enzyme's pyridoxal 5'-phosphate binding mechanism.
Area of Science:
- Enzymology
- Structural Biology
- Biochemistry
Background:
- Tyrosine phenol-lyase (TPL) is a pyridoxal 5 étaire-phosphate (PLP)-dependent enzyme.
- Understanding TPL's structure is crucial for elucidating its catalytic mechanism.
Purpose of the Study:
- To clone and determine the primary sequence of TPL from Citrobacter freundii.
- To elucidate the three-dimensional structure of TPL and identify the PLP-binding site.
Main Methods:
- Gene cloning and DNA sequencing to determine the primary amino acid sequence.
- Peptide purification and sequencing after chemical modification of the holoenzyme.
- X-ray crystallography of the apotyrosine phenol-lyase at 2.3-A resolution using synchrotron radiation.
Main Results:
- The primary sequence of TPL was deduced and confirmed by peptide sequencing.
- The crystal structure revealed a tetrameric molecule with 222 symmetry.
- Lysine 257 (K257) was identified as the PLP-binding residue, located at the domain interface.
- The overall fold and active site resemble those of aminotransferases, with conserved PLP-binding residues.
Conclusions:
- The study provides the complete primary sequence and high-resolution crystal structure of tyrosine phenol-lyase.
- Structural analysis reveals conserved features with aminotransferases, particularly in the PLP-binding domain.
- The findings offer insights into the catalytic mechanism and evolutionary relationships of PLP-dependent enzymes.