1uxj: Difference between revisions

Revision as of 16:29, 21 February 2008

LARGE IMPROVEMENT IN THE THERMAL STABILITY OF A TETRAMERIC MALATE DEHYDROGENASE BY SINGLE POINT MUTATIONS AT THE DIMER-DIMER INTERFACE

OverviewOverview

The stability of tetrameric malate dehydrogenase from the green phototrophic bacterium Chloroflexus aurantiacus (CaMDH) is at least in part determined by electrostatic interactions at the dimer-dimer interface. Since previous studies had indicated that the thermal stability of CaMDH becomes lower with increasing pH, attempts were made to increase the stability by removal of (excess) negative charge at the dimer-dimer interface. Mutation of Glu165 to Gln or Lys yielded a dramatic increase in thermal stability at pH 7.5 (+23.6 -- + 23.9 degrees C increase in apparent t(m)) and a more moderate increase at pH 4.4 (+4.6 -- + 5.4 degrees C). The drastically increased stability at neutral pH was achieved without forfeiture of catalytic performance at low temperatures. The crystal structures of the two mutants showed only minor structural changes close to the mutated residues, and indicated that the observed stability effects are solely due to subtle changes in the complex network of electrostatic interactions in the dimer-dimer interface. Both mutations reduced the concentration dependency of thermal stability, suggesting that the oligomeric structure had been reinforced. Interestingly, the two mutations had similar effects on stability, despite the charge difference between the introduced side-chains. Together with the loss of concentration dependency, this may indicate that both E165Q and E165K stabilize CaMDH to such an extent that disruption of the inter-dimer electrostatic network around residue 165 no longer limits kinetic thermal stability.

About this StructureAbout this Structure

1UXJ is a Single protein structure of sequence from Chloroflexus aurantiacus with , , and as ligands. Active as Malate dehydrogenase, with EC number 1.1.1.37 Known structural/functional Site: . Full crystallographic information is available from OCA.

ReferenceReference

Large improvement in the thermal stability of a tetrameric malate dehydrogenase by single point mutations at the dimer-dimer interface., Bjork A, Dalhus B, Mantzilas D, Sirevag R, Eijsink VG, J Mol Biol. 2004 Aug 27;341(5):1215-26. PMID:15321717

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 ==Overview==
-The stability of tetrameric malate dehydrogenase from the green, phototrophic bacterium Chloroflexus aurantiacus (CaMDH) is at least in, part determined by electrostatic interactions at the dimer-dimer, interface. Since previous studies had indicated that the thermal stability, of CaMDH becomes lower with increasing pH, attempts were made to increase, the stability by removal of (excess) negative charge at the dimer-dimer, interface. Mutation of Glu165 to Gln or Lys yielded a dramatic increase in, thermal stability at pH 7.5 (+23.6 -- + 23.9 degrees C increase in, apparent t(m)) and a more moderate increase at pH 4.4 (+4.6 -- + 5.4, degrees C). The drastically increased stability at neutral pH was achieved, without forfeiture of catalytic performance at low temperatures. The, crystal structures of the two mutants showed only minor structural changes, close to the mutated residues, and indicated that the observed stability, effects are solely due to subtle changes in the complex network of, electrostatic interactions in the dimer-dimer interface. Both mutations, reduced the concentration dependency of thermal stability, suggesting that, the oligomeric structure had been reinforced. Interestingly, the two, mutations had similar effects on stability, despite the charge difference, between the introduced side-chains. Together with the loss of, concentration dependency, this may indicate that both E165Q and E165K, stabilize CaMDH to such an extent that disruption of the inter-dimer, electrostatic network around residue 165 no longer limits kinetic thermal, stability.
+The stability of tetrameric malate dehydrogenase from the green phototrophic bacterium Chloroflexus aurantiacus (CaMDH) is at least in part determined by electrostatic interactions at the dimer-dimer interface. Since previous studies had indicated that the thermal stability of CaMDH becomes lower with increasing pH, attempts were made to increase the stability by removal of (excess) negative charge at the dimer-dimer interface. Mutation of Glu165 to Gln or Lys yielded a dramatic increase in thermal stability at pH 7.5 (+23.6 -- + 23.9 degrees C increase in apparent t(m)) and a more moderate increase at pH 4.4 (+4.6 -- + 5.4 degrees C). The drastically increased stability at neutral pH was achieved without forfeiture of catalytic performance at low temperatures. The crystal structures of the two mutants showed only minor structural changes close to the mutated residues, and indicated that the observed stability effects are solely due to subtle changes in the complex network of electrostatic interactions in the dimer-dimer interface. Both mutations reduced the concentration dependency of thermal stability, suggesting that the oligomeric structure had been reinforced. Interestingly, the two mutations had similar effects on stability, despite the charge difference between the introduced side-chains. Together with the loss of concentration dependency, this may indicate that both E165Q and E165K stabilize CaMDH to such an extent that disruption of the inter-dimer electrostatic network around residue 165 no longer limits kinetic thermal stability.
 ==About this Structure==
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 [[Category: Bjork, A.]]
 [[Category: Dalhus, B.]]
-[[Category: Eijsink, V.G.H.]]
+[[Category: Eijsink, V G.H.]]
 [[Category: Mantzilas, D.]]
 [[Category: Sirevag, R.]]
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 [[Category: tricarboxylic acid cycle]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Feb  3 10:12:10 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:29:23 2008''