1eb4

From Proteopedia

Revision as of 14:04, 5 November 2007

HISTIDINE AMMONIA-LYASE (HAL) MUTANT F329A FROM PSEUDOMONAS PUTIDA

Overview

Histidine ammonia-lyase requires a 4-methylidene-imidazole-5-one group, (MIO) that is produced autocatalytically by a cyclization and dehydration, step in a 3-residue loop of the polypeptide. The crystal structures of, three mutants have been established. Two mutants were inactive and failed, to form MIO, but remained unchanged elsewhere. The third mutant showed, very low activity and formed MIO, although it differed from an MIO-less, mutant only by an additional 329-C(beta) atom. This atom forms one, constraint during MIO formation, the other being the strongly connected, Asp145. An exploration of the conformational space of the MIO-forming loop, showed that the cyclization is probably enforced by a mechanic compression, in a late stage of chain folding and is catalyzed by a well-connected, internal water molecule. The cyclization of the respective 3-residue loop, of green fluorescent protein is likely to occur in a similar reaction.

About this Structure

1EB4 is a Single protein structure of sequence from Pseudomonas putida with SO4 and GOL as ligands. Active as Histidine ammonia-lyase, with EC number 4.3.1.3 Structure known Active Site: AC1. Full crystallographic information is available from OCA.

Reference

Autocatalytic peptide cyclization during chain folding of histidine ammonia-lyase., Baedeker M, Schulz GE, Structure. 2002 Jan;10(1):61-7. PMID:11796111

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