Quick Search:

uzh logo
Browse by:
bullet
bullet
bullet
bullet

Zurich Open Repository and Archive

Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-24624

Raschle, T; Arigoni, D; Brunisholz, R; Rechsteiner, H; Amrhein, N; Fitzpatrick, T B (2007). Reaction mechanism of pyridoxal 5'-phosphate synthase: detection of an enzyme-bound chromophoric intermediate. Journal of Biological Chemistry, 282(9):6098-6105.

[img]
Preview
Accepted Version
PDF
2MB

View at publisher

Abstract

Vitamin B6 is an essential metabolite in all organisms. De novo synthesis of the vitamin can occur through either of two mutually exclusive pathways referred to as deoxyxylulose 5-phosphate-dependent and deoxyxylulose 5-phosphate-independent. The latter pathway has only recently been discovered and is distinguished by the presence of two genes, Pdx1 and Pdx2, encoding the synthase and glutaminase subunit of PLP synthase, respectively. In the presence of ammonia, the synthase alone displays an exceptional polymorphic synthetic ability in carrying out a complex set of reactions, including pentose and triose isomerization, imine formation, ammonia addition, aldol-type condensation, cyclization, and aromatization, that convert C3 and C5 precursors into the cofactor B6 vitamer, pyridoxal 5'-phosphate. Here, employing the Bacillus subtilis proteins, we demonstrate key features along the catalytic path. We show that ribose 5-phosphate is the preferred C5 substrate and provide unequivocal evidence that the pent(ul)ose phosphate imine occurs at lysine 81 rather than lysine 149 as previously postulated. While this study was under review, corroborative crystallographic evidence has been provided for imine formation with the corresponding lysine group in the enzyme from Thermotoga maritima (Zein, F., Zhang, Y., Kang, Y.-N., Burns, K., Begley, T. P., and Ealick, S. E. (2006) Biochemistry 45, 14609-14620). We have detected an unanticipated covalent reaction intermediate that occurs subsequent to imine formation and is dependent on the presence of Pdx2 and glutamine. This step most likely primes the enzyme for acceptance of the triose sugar, ultimately leading to formation of the pyridine ring. Two alternative structures are proposed for the chromophoric intermediate, both of which require substantial modifications of the proposed mechanism.

Citations

29 citations in Web of Science®
31 citations in Scopus®
Google Scholar™

Altmetrics

Downloads

38 downloads since deposited on 18 Dec 2009
6 downloads since 12 months

Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Functional Genomics Center Zurich
08 University Research Priority Programs > Systems Biology / Functional Genomics
DDC:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2 March 2007
Deposited On:18 Dec 2009 13:12
Last Modified:27 Nov 2013 22:51
Publisher:American Society for Biochemistry and Molecular Biology
ISSN:0021-9258
Publisher DOI:10.1074/jbc.M610614200
PubMed ID:17189272

Users (please log in): suggest update or correction for this item

Repository Staff Only: item control page