Universität zu Köln

Hojgaard, Casper ORCID: 0000-0002-1258-1717, Kofoed, Christian ORCID: 0000-0002-8258-5887, Espersen, Roall, Johansson, Kristoffer Enoe ORCID: 0000-0001-6054-0461, Villa, Mara ORCID: 0000-0003-2543-027X, Willemoes, Martin ORCID: 0000-0003-1689-2712, Lindorff-Larsen, Kresten ORCID: 0000-0002-4750-6039, Teilum, Kaare ORCID: 0000-0001-6919-1982 and Winther, Jakob R. (2016). A Soluble, Folded Protein without Charged Amino Acid Residues. Biochemistry, 55 (28). S. 3949 - 3957. WASHINGTON: AMER CHEMICAL SOC. ISSN 0006-2960

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Abstract

Charges are considered an integral part of protein structure and function, enhancing solubility and providing specificity in molecular interactions. We wished to investigate whether charged amino acids are indeed required for protein biogenesis and whether a protein completely free of titratable side chains can maintain solubility, stability, and function. As a model, we used a cellulose-binding domain from Cellulomonas fimi, which, among proteins of more than 100 amino acids, presently is the least charged in the Protein Data Bank, with a total of only four titratable residues. We find that the protein shows a surprising resilience toward extremes of pH, demonstrating stability and function (cellulose binding) in the pH range from 2 to 11. To ask whether the four charged residues present were required for these properties of this protein, we altered them to nontitratable ones. Remarkably, this chargeless protein is produced reasonably well in :Escherichia coli, retains its stable three-dimensional structure, and is still capable of strong cellulose binding. To further deprive this protein of charges, we removed the N-terminal charge by acetylation and studied the protein at pH 2, where the C-terminus is effectively protonated, Under these conditions, the protein retains its function and proved to be both soluble and have a reversible folding-unfolding transition. To the best of our knowledge, this is the first time a soluble, functional protein with no titratable side chains has been produced.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Hojgaard, Casper UNSPECIFIED orcid.org/0000-0002-1258-1717 UNSPECIFIED Kofoed, Christian UNSPECIFIED orcid.org/0000-0002-8258-5887 UNSPECIFIED Espersen, Roall UNSPECIFIED UNSPECIFIED UNSPECIFIED Johansson, Kristoffer Enoe UNSPECIFIED orcid.org/0000-0001-6054-0461 UNSPECIFIED Villa, Mara UNSPECIFIED orcid.org/0000-0003-2543-027X UNSPECIFIED Willemoes, Martin UNSPECIFIED orcid.org/0000-0003-1689-2712 UNSPECIFIED Lindorff-Larsen, Kresten UNSPECIFIED orcid.org/0000-0002-4750-6039 UNSPECIFIED Teilum, Kaare UNSPECIFIED orcid.org/0000-0001-6919-1982 UNSPECIFIED Winther, Jakob R. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-269778
DOI:	10.1021/acs.biochem.6b00269
Journal or Publication Title:	Biochemistry
Volume:	55
Number:	28
Page Range:	S. 3949 - 3957
Date:	2016
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	0006-2960
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CARBOHYDRATE-BINDING MODULE; SURFACE SALT BRIDGES; CELLULOMONAS-FIMI; ELECTROSTATIC INTERACTIONS; SOLUBILITY; STABILITY; DOMAIN; STABILIZATION; AGGREGATION; CONTRIBUTE Multiple languages Biochemistry & Molecular Biology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/26977