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Biophys J. 2005 Apr;88(4):2823-32. Epub 2005 Jan 14.

Protein disorder: conformational distribution of the flexible linker in a chimeric double cellulase.

Author information

1
Novozymes A/S, Bagsvaerd, Denmark.

Abstract

The structural properties of the linker peptide connecting the cellulose-binding module to the catalytic module in bimodular cellulases have been investigated by small-angle x-ray scattering. Since the linker and the cellulose-binding module are relatively small and cannot be readily detected separately, the conformation of the linker was studied by means of an artificial fusion protein, Cel6BA, in which an 88-residue linker connects the large catalytic modules of the cellulases Cel6A and Cel6B from Humicola insolens. Our data showed that Cel6BA is very elongated with a maximum dimension of 178 A, but could not be described by a single conformation. Modeling of a series of Cel6BA conformers with interdomain separations ranging between 10 A and 130 A showed that good Guinier and P(r) profile fits were obtained by a weighted average of the scattering curves of all the models where the linker follows a nonrandom distribution, with a preference for the more compact conformers. These structural properties are likely to be essential for the function of the linker as a molecular spring between the two functional modules. Small-angle x-ray scattering therefore provides a unique tool to quantitatively analyze the conformational disorder typical of proteins described as natively unfolded.

PMID:
15653742
PMCID:
PMC1305377
DOI:
10.1529/biophysj.104.050146
[Indexed for MEDLINE]
Free PMC Article

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