1pt1

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spinqualitylabelsall models 1pt1, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Unprocessed Pyruvoyl Dependent Aspartate Decarboxylase with Histidine 11 Mutated to Alanine

Overview

Aspartate decarboxylase, which is translated as a pro-protein, undergoes, intramolecular self-cleavage at Gly24-Ser25. We have determined the, crystal structures of an unprocessed native precursor, in addition to, Ala24 insertion, Ala26 insertion and Gly24-->Ser, His11-->Ala, Ser25-->Ala, Ser25-->Cys and Ser25-->Thr mutants. Comparative analyses of, the cleavage site reveal specific conformational constraints that govern, self-processing and demonstrate that considerable rearrangement must, occur. We suggest that Thr57 Ogamma and a water molecule form an 'oxyanion, hole' that likely stabilizes the proposed oxyoxazolidine intermediate., Thr57 and this water molecule are probable catalytic residues able to, support acid-base catalysis. The conformational freedom in the loop, preceding the cleavage site appears to play a determining role in the, reaction. The molecular mechanism of self-processing, presented here, emphasizes the importance of stabilization of the oxyoxazolidine, intermediate. Comparison of the structural features shows significant, similarity to those in other self-processing systems, and suggests that, models of the cleavage site of such enzymes based on Ser-->Ala or, Ser-->Thr mutants alone may lead to erroneous interpretations of the, mechanism.

About this Structure

1PT1 is a Single protein structure of sequence from Escherichia coli with SO4 as ligand. Active as Aspartate 1-decarboxylase, with EC number 4.1.1.11 Full crystallographic information is available from OCA.

Reference

Structural constraints on protein self-processing in L-aspartate-alpha-decarboxylase., Schmitzberger F, Kilkenny ML, Lobley CM, Webb ME, Vinkovic M, Matak-Vinkovic D, Witty M, Chirgadze DY, Smith AG, Abell C, Blundell TL, EMBO J. 2003 Dec 1;22(23):6193-204. PMID:14633979

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