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'''CRYSTAL STRUCTURE OF MALE31, A DEFECTIVE FOLDING MUTANT OF MALTOSE-BINDING PROTEIN''' | '''CRYSTAL STRUCTURE OF MALE31, A DEFECTIVE FOLDING MUTANT OF MALTOSE-BINDING PROTEIN''' | ||
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[[Category: Sassoon, N.]] | [[Category: Sassoon, N.]] | ||
[[Category: Saul, F A.]] | [[Category: Saul, F A.]] | ||
[[Category: | [[Category: Misfolding mutant]] | ||
[[Category: | [[Category: Sugar transport]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 23:44:10 2008'' | |||
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Revision as of 23:44, 2 May 2008
CRYSTAL STRUCTURE OF MALE31, A DEFECTIVE FOLDING MUTANT OF MALTOSE-BINDING PROTEIN
OverviewOverview
Maltose-binding protein (MBP or MalE) of Escherichia coli is the periplasmic receptor of the maltose transport system. MalE31, a defective folding mutant of MalE carrying sequence changes Gly 32-->Asp and Ile 33-->Pro, is either degraded or forms inclusion bodies following its export to the periplasmic compartment. We have shown previously that overexpression of FkpA, a heat-shock periplasmic peptidyl-prolyl isomerase with chaperone activity, suppresses MalE31 misfolding. Here, we have exploited this property to characterize the maltose transport activity of MalE31 in whole cells. MalE31 displays defective transport behavior, even though it retains maltose-binding activity comparable with that of the wild-type protein. Because the mutated residues are in a region on the surface of MalE not identified previously as important for maltose transport, we have solved the crystal structure of MalE31 in the maltose-bound state in order to characterize the effects of these changes. The structure was determined by molecular replacement methods and refined to 1.85 A resolution. The conformation of MalE31 closely resembles that of wild-type MalE, with very small displacements of the mutated residues located in the loop connecting the first alpha-helix to the first beta-strand. The structural and functional characterization provides experimental evidence that MalE31 can attain a wild-type folded conformation, and suggest that the mutated sites are probably involved in the interactions with the membrane components of the maltose transport system.
About this StructureAbout this Structure
1LAX is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of a defective folding protein., Saul FA, Mourez M, Vulliez-Le Normand B, Sassoon N, Bentley GA, Betton JM, Protein Sci. 2003 Mar;12(3):577-85. PMID:12592028 Page seeded by OCA on Fri May 2 23:44:10 2008