3upb

Publication Abstract from PubMed

Arabinose 5-phosphate (A5P) is the aldopentose version of the ketohexose fructose 6-phosphate (F6P), having identical stereochemistry but lacking atoms corresponding to the 1-carbon and 1-hydroxyl. Despite structural similarity and conservation of the reactive portion of F6P, F6P acts as a substrate whereas A5P is reported to be an inhibitor of transaldolase. To address the lack of A5P reactivity we determined a crystal structure of the Francisella tularensis transaldolase in complex with A5P. This structure reveals that like F6P, A5P forms a covalent Schiff base with active site Lys135. Unlike F6P, A5P binding fails to displace an ordered active site water molecule. Retaining this water necessitates conformational changes at the A5P-protein linkage that possibly hinder reactivity. The findings presented here show the basis of A5P inhibition and suggest an unusual mechanism of competitive, reversible-covalent transaldolase regulation.

Arabinose 5-phosphate covalently inhibits transaldolase.,Light SH, Anderson WF J Struct Funct Genomics. 2014 Mar;15(1):41-4. doi: 10.1007/s10969-014-9174-1., Epub 2014 Feb 9. PMID:24510200^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.