1ibt: Difference between revisions
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'''STRUCTURE OF THE D53,54N MUTANT OF HISTIDINE DECARBOXYLASE AT-170 C''' | '''STRUCTURE OF THE D53,54N MUTANT OF HISTIDINE DECARBOXYLASE AT-170 C''' | ||
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[[Category: Schelp, E.]] | [[Category: Schelp, E.]] | ||
[[Category: Worley, S.]] | [[Category: Worley, S.]] | ||
[[Category: | [[Category: Carboxy-lyase]] | ||
[[Category: | [[Category: Helix disorder]] | ||
[[Category: | [[Category: Less active form]] | ||
[[Category: | [[Category: Pyruvoyl]] | ||
[[Category: | [[Category: Site-directed mutant]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 19:49:17 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 19:49, 2 May 2008
STRUCTURE OF THE D53,54N MUTANT OF HISTIDINE DECARBOXYLASE AT-170 C
OverviewOverview
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 StructureAbout this Structure
1IBT is a Protein complex structure of sequences from Lactobacillus sp.. Full crystallographic information is available from OCA.
ReferenceReference
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 Fri May 2 19:49:17 2008