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Folding behavior of a backbone-reversed protein: reversible polyproline type II to beta-sheet thermal transitions in retro-GroES multimers with GroES-like features.

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title Folding behavior of a backbone-reversed protein: reversible polyproline type II to beta-sheet thermal transitions in retro-GroES multimers with GroES-like features.
 
Creator Ahmed, Shubbir
Shukla, Anshuman
Guptasarma, Purnananda
 
Subject QH301 Biology
 
Description The structural consequences of the reversal of polypeptide backbone direction (retro modification) remain insufficiently explored. Here, we describe the behavior of an engineered, backbone-reversed form of the 97 residues-long GroES co-chaperonin of Escherichia coli. FTIR and far-UV CD spectroscopy suggest that retro-GroES adopts a mixed polyproline type II (PPII)-beta-strand structure with a beta(II) type CD spectrum similar to that of GroES. Gel-filtration chromatography reveals that the protein adopts trimeric and/or pentameric quaternary structures, with solubility retained up to concentrations of 5.0-5.5 mg/ml in aqueous solutions. Mutations inserting a single tryptophan residue as a spectroscopic probe at three different sites cause no perturbation in the protein's CD spectral characteristics, or in its quaternary structural status. The protein is cooperatively dissociated, and non-cooperatively unfolded, by both guanidine hydrochloride and urea. Intriguingly, unlike with GroES, retro-GroES is not unfolded by heat. Instead, there is a reversible structural transition involving conversion of PPII structure to beta sheet structure, upon heating, with no attendant aggregation even at 90 degrees C. Retro-GroES does not bind GroEL. In summary, some structure-forming characteristics of GroES appear to be conserved through the backbone reversal process, although the differential conformational behavior upon heating also indicates differences.
 
Publisher Elsevier Science
 
Date 2008-06
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://crdd.osdd.net/open/612/1/guptasarma08.11.pdf
Ahmed, Shubbir and Shukla, Anshuman and Guptasarma, Purnananda (2008) Folding behavior of a backbone-reversed protein: reversible polyproline type II to beta-sheet thermal transitions in retro-GroES multimers with GroES-like features. Biochimica et biophysica acta, 1784 (6). pp. 916-23. ISSN 0006-3002
 
Relation http://www.sciencedirect.com/science/article/pii/S1570963908000721
http://crdd.osdd.net/open/612/