1lax

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spinqualitylabelsall models 1lax, resolution 1.85Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTAL STRUCTURE OF MALE31, A DEFECTIVE FOLDING MUTANT OF MALTOSE-BINDING PROTEIN

Overview

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 Structure

1LAX is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

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

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