Investigating the active site of human trimethyllysine hydroxylase

Yali Wang, Y Vijayendar Reddy, Abbas H K Al Temimi, Hanka Venselaar, Frank H T Nelissen, Danny C Lenstra, Jasmin Mecinović

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Abstrakt

The biologically important carnitine biosynthesis pathway in humans proceeds via four enzymatic steps. The first step in carnitine biosynthesis is catalyzed by trimethyllysine hydroxylase (TMLH), a non-heme Fe(II) and 2-oxoglutarate (2OG) dependent oxygenase, which catalyzes the stereospecific hydroxylation of (2 S )- Nε-trimethyllysine to (2 S ,3 S )-3-hydroxy- Nε-trimethyllysine. Here, we report biocatalytic studies on human TMLH and its 19 variants introduced through site-directed mutagenesis. Amino acid substitutions at the sites involved in binding of the Fe(II) cofactor, 2OG cosubstrate, and (2 S )- Nε-trimethyllysine substrate provide a basic insight into the binding requirements that determine an efficient TMLH-catalyzed conversion of (2 S )- Nε-trimethyllysine to (2 S ,3 S )-3-hydroxy- Nε-trimethyllysine. This work demonstrates the importance of the recognition sites that contribute to the enzymatic activity of TMLH: the Fe(II)-binding H242-D244-H389 residues, R391-R398 involved in 2OG-binding, and several residues (D231, N334, and the aromatic cage comprised of W221, Y217 and Y234) associated with binding of (2 S )- Nε-trimethyllysine.

OriginalsprogEngelsk
TidsskriftThe Biochemical journal
Vol/bind476
Udgave nummer7
Sider (fra-til)1109-1119
ISSN0264-6021
DOI
StatusUdgivet - 10. apr. 2019

Bibliografisk note

©2019 The Author(s).

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