Crystal Structure of Citrobacter freundii Asp214Ala Tyrosine Phenollyase Reveals that Asp214 is Critical for Maintaining a Strain in the Internal Aldimine

Milić, Dalibor and Demidkina, Tatyana V. and Zakomirdina, Lyudmila N. and Matković-Čalogović, Dubravka and Antson, Alfred A. (2012) Crystal Structure of Citrobacter freundii Asp214Ala Tyrosine Phenollyase Reveals that Asp214 is Critical for Maintaining a Strain in the Internal Aldimine. Croatica Chemica Acta, 85 (3). pp. 283-288. ISSN 0011-1643

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Abstract

Tyrosine phenol-lyase (TPL) is a pyridoxal-5′-phosphate (PLP) dependent enzyme which catalyzes β-elimination of L-tyrosine. In the holoenzyme the protonated pyridinium N1 atom of the PLP cofactor is hydrogen-bonded to the side chain of Asp214. Here we report the X-ray structure of C. freundii D214A TPL determined at 1.9 Å resolution. Comparison with the structure of the wild-type TPL shows that the D214A replacement induced significant conformational reorganization in the active site leading to its partial closure. Significantly, in D214A TPL the strain in the internal aldimine is completely released and the pyridine N1 atom of PLP is deprotonated. These observations explain the considerably reduced activity of the D214A TPL towards its substrates [T. V. Demidkina et al., Biochim. Biophys. Acta, Proteins Proteomics 1764 (2006) 1268–1276]. The reported structure reveals that Asp214 is critical for maintaining the strain in the internal aldimine. We argue that this strain is used by the enzyme to accelerate the transaldimination reaction, the first step in the enzymatic catalysis.

Item Type: Article
Keywords: tyrosine phenol-lyase; chemical strain; internal aldimine; pyridoxal 5′-phosphate; X-ray structure
Date: 2012
Subjects: NATURAL SCIENCES > Chemistry
Divisions: Faculty of Science > Department of Chemistry
Publisher: Hrvatsko kemijsko društvo
Related URLs:
Depositing User: Branka Maravic
Date Deposited: 25 Apr 2014 11:02
Last Modified: 25 Apr 2014 11:02
URI: http://digre.pmf.unizg.hr/id/eprint/975

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