1ibv
From Proteopedia
|
STRUCTURE OF THE D53,54N MUTANT OF HISTIDINE DECARBOXYLASE BOUND WITH HISTIDINE METHYL ESTER AT-170 C
Overview
Histidine decarboxylase (HDC) from Lactobacillus 30a converts histidine to, histamine, a process that enables the bacteria to maintain the optimum pH, range for cell growth. HDC is regulated by pH; it is active at low pH and, inactive at neutral to alkaline pH. The X-ray structure of HDC at pH 8, revealed that a helix was disordered, resulting in the disruption of the, substrate-binding site. The HDC trimer has also been shown to exhibit, cooperative kinetics at neutral pH, that is, histidine can trigger a, T-state to R-state transition. The D53,54N mutant of HDC has an elevated, Km, even at low pH, indicating that the enzyme assumes the low activity, T-state. We have solved the structures of the D53,54N mutant at low pH, with and without the substrate analog histidine methyl ester (HME) bound., Structural analysis shows that the apo-D53,54N mutant is in the inactive, or T-state and that binding of the substrate analog induces the enzyme to, adopt the active or R-state. A mechanism for the cooperative transition is, proposed.
About this Structure
1IBV is a Protein complex structure of sequences from Lactobacillus sp. with PVH as ligand. Active as Histidine decarboxylase, with EC number 4.1.1.22 Full crystallographic information is available from OCA.
Reference
Structure and cooperativity of a T-state mutant of histidine decarboxylase from Lactobacillus 30a., Worley S, Schelp E, Monzingo AF, Ernst S, Robertus JD, Proteins. 2002 Feb 15;46(3):321-9. PMID:11835507
Page seeded by OCA on Tue Nov 20 17:16:19 2007
