X-ray crystal structure of Saccharomyces cerevisiae Pdx1 provides insights into the oligomeric nature of PLP synthases

Neuwirth, Martina; Strohmeier, Marco; Windeisen, Volker; Wallner, Silvia; Deller, Sigrid; Rippe, Karsten; Sinning, Irmgard; Macheroux, Peter; Tews, Ivo

doi:10.1016/j.febslet.2009.06.009

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Volume 583, Issue 13 , Pages 2179-2186, 7 July 2009

X-ray crystal structure of Saccharomyces cerevisiae Pdx1 provides insights into the oligomeric nature of PLP synthases

Edited by Hans Eklund

Martina Neuwirth
- Technische Universität Graz, Institut für Biochemie, Petersgasse 12/2, A-8010 Graz, Austria
- These authors contributed equally to this work.
Marco Strohmeier
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
- These authors contributed equally to this work.
Volker Windeisen
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
Silvia Wallner
- Technische Universität Graz, Institut für Biochemie, Petersgasse 12/2, A-8010 Graz, Austria
Sigrid Deller
- Technische Universität Graz, Institut für Biochemie, Petersgasse 12/2, A-8010 Graz, Austria
Karsten Rippe
- Deutsches Krebsforschungszentrum and BIOQUANT, Research Group Genome Organization & Function, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
Peter Macheroux
- Technische Universität Graz, Institut für Biochemie, Petersgasse 12/2, A-8010 Graz, Austria
- Corresponding authors. Fax: +43 316 8736 952 (P. Macheroux); +49 6221 5447 90 (I. Tews).
Ivo Tews
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany
- Corresponding authors. Fax: +43 316 8736 952 (P. Macheroux); +49 6221 5447 90 (I. Tews).

Received 20 October 2008; received in revised form 1 June 2009; accepted 4 June 2009. published online 11 June 2009.

Abstract

The universal enzymatic cofactor vitamin B6 can be synthesized as pyridoxal 5-phosphate (PLP) by the glutamine amidotransferase Pdx1. We show that Saccharomyces cerevisiae Pdx1 is hexameric by analytical ultracentrifugation and by crystallographic 3D structure determination. Bacterial homologues were previously reported to exist in hexamer:dodecamer equilibrium. A small sequence insertion found in yeast Pdx1 elevates the dodecamer dissociation constant when introduced into Bacillus subtilis Pdx1. Further, we demonstrate that the yeast Pdx1 C-terminus contacts an adjacent subunit, and deletion of this segment decreases enzymatic activity 3.5-fold, suggesting a role in catalysis.