X-ray crystal structure of Saccharomyces cerevisiae Pdx1 provides insights into the oligomeric nature of PLP synthases.
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.
Neuwirth
Martina
M
Technische Universität Graz, Institut für Biochemie, Graz, Austria.
Strohmeier
Marco
M
Windeisen
Volker
V
Wallner
Silvia
S
Deller
Sigrid
S
Rippe
Karsten
K
Sinning
Irmgard
I
Macheroux
Peter
P
Tews
Ivo
I
D001412:Bacillus subtilis / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D005972:Glutaminase / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D011768:Pyruvate Dehydrogenase Complex / Q000737:chemistry* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity
D001426:Bacterial Proteins; C489060:PDX1 protein, S cerevisiae; D021122:Protein Subunits; D011768:Pyruvate Dehydrogenase Complex; D029701:Saccharomyces cerevisiae Proteins; D005972:Glutaminase