Universität zu Köln

Oecal, Sinan, Socher, Eileen ORCID: 0000-0002-6239-3749, Uthoff, Matthias ORCID: 0000-0002-6477-5505, Ernst, Corvin, Zaucke, Frank, Sticht, Heinrich ORCID: 0000-0001-5644-045X, Baumann, Ulrich and Gebauer, Jan M. (2016). The pH-dependent Client Release from the Collagen-specific Chaperone HSP47 Is Triggered by a Tandem Histidine Pair. J. Biol. Chem., 291 (24). S. 12612 - 12627. BETHESDA: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC. ISSN 1083-351X

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Abstract

Heat shock protein 47 (HSP47) is an endoplasmic reticulum (ER)-resident collagen-specific chaperone and essential for proper formation of the characteristic collagen triple helix. It preferentially binds to the folded conformation of its clients and accompanies them from the ER to the Golgi compartment, where it releases them and is recycled back to the ER. Unlike other chaperones, the binding and release cycles are not governed by nucleotide exchange and hydrolysis, but presumably the dissociation of the HSP47-procollagen complex is triggered by the lower pH in the Golgi (pH 6.3) compared with the ER (pH 7.4). Histidine residues have been suggested as triggers due to their approximate textbook pK(a) value of 6.1 for their side chains. We present here an extensive theoretical and experimental study of the 14 histidine residues present in canine HSP47, where we have mutated all histidine residues in the collagen binding interface and additionally all of those that were predicted to undergo a significant change in protonation state between pH 7 and 6. These mutants were characterized by bio-layer interferometry for their pH-dependent binding to a collagen model. One mutant (H238N) loses binding, which can be explained by a rearrangement of the Arg(222) and Asp(385) residues, which are crucial for specific collagen recognition. Most of the other mutants were remarkably silent, but a double mutant with His(273) and His(274) exchanged for asparagines exhibits a much less pronounced pH dependence of collagen binding. This effect is mainly caused by a lower k(off) at the low pH values.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Oecal, Sinan UNSPECIFIED UNSPECIFIED UNSPECIFIED Socher, Eileen UNSPECIFIED orcid.org/0000-0002-6239-3749 UNSPECIFIED Uthoff, Matthias UNSPECIFIED orcid.org/0000-0002-6477-5505 UNSPECIFIED Ernst, Corvin UNSPECIFIED UNSPECIFIED UNSPECIFIED Zaucke, Frank UNSPECIFIED UNSPECIFIED UNSPECIFIED Sticht, Heinrich UNSPECIFIED orcid.org/0000-0001-5644-045X UNSPECIFIED Baumann, Ulrich UNSPECIFIED UNSPECIFIED UNSPECIFIED Gebauer, Jan M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-272366
DOI:	10.1074/jbc.M115.706069
Journal or Publication Title:	J. Biol. Chem.
Volume:	291
Number:	24
Page Range:	S. 12612 - 12627
Date:	2016
Publisher:	AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Place of Publication:	BETHESDA
ISSN:	1083-351X
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Biochemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PROTEIN SECONDARY STRUCTURE; HEAT-SHOCK-PROTEIN; MOLECULAR CHAPERONE; CIRCULAR-DICHROISM; I COLLAGEN; BINDING; RECOGNITION; STABILITY; EVOLUTION; PROTOCOL Multiple languages Biochemistry & Molecular Biology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/27236