1ibt: Difference between revisions

Revision as of 14:10, 21 February 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.. Active as Histidine decarboxylase, with EC number 4.1.1.22 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 Thu Feb 21 13:10:08 2008

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OCA

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-[[Image:1ibt.jpg|left|200px]]<br /><applet load="1ibt" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1ibt.jpg|left|200px]]<br /><applet load="1ibt" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1ibt, resolution 2.6&Aring;" />
 '''STRUCTURE OF THE D53,54N MUTANT OF HISTIDINE DECARBOXYLASE AT-170 C'''<br />
 ==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.
+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==
-IBT is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Lactobacillus_sp. Lactobacillus sp.]. Active as [http://en.wikipedia.org/wiki/Histidine_decarboxylase Histidine decarboxylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.1.22 4.1.1.22] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1IBT OCA].
+IBT is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Lactobacillus_sp. Lactobacillus sp.]. Active as [http://en.wikipedia.org/wiki/Histidine_decarboxylase Histidine decarboxylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.1.22 4.1.1.22] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IBT OCA].
 ==Reference==
@@ Line 15: / Line 15: @@
 [[Category: Protein complex]]
 [[Category: Ernst, S.]]
-[[Category: Monzingo, A.F.]]
+[[Category: Monzingo, A F.]]
-[[Category: Robertus, J.D.]]
+[[Category: Robertus, J D.]]
 [[Category: Schelp, E.]]
 [[Category: Worley, S.]]
@@ Line 25: / Line 25: @@
 [[Category: site-directed mutant]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 17:16:10 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:10:08 2008''