1pyu

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

Processed Aspartate Decarboxylase Mutant with Ser25 mutated to Cys

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

1PYU is a Protein complex structure of sequences from Escherichia coli with 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

Page seeded by OCA on Thu Feb 21 14:34:01 2008