Title

Replacement Of The Axial Copper Ligand Methionine With Lysine In Amicyanin Converts It To A Zinc-Binding Protein That No Longer Binds Copper

Keywords

Cupredoxin; Metalloprotein; Protein folding; X-ray structure

Abstract

The mutation of the axial ligand of the type I copper protein amicyanin from Met to Lys results in a protein that is spectroscopically invisible and redox inactive. M98K amicyanin acts as a competitive inhibitor in the reaction of native amicyanin with methylamine dehydrogenase indicating that the M98K mutation has not affected the affinity for its natural electron donor. The crystal structure of M98K amicyanin reveals that its overall structure is very similar to native amicyanin but that the type I binding site is occupied by zinc. Anomalous difference Fourier maps calculated using the data collected around the absorption edges of copper and zinc confirm the presence of Zn 2+ at the type I site. The Lys98 NZ donates a hydrogen bond to a well-ordered water molecule at the type I site which enhances the ability of Lys98 to provide a ligand for Zn 2+. Attempts to reconstitute M98K apoamicyanin with copper resulted in precipitation of the protein. The fact that the M98K mutation generated such a selective zinc-binding protein was surprising as ligation of zinc by Lys is rare and this ligand set is unique for zinc. © 2011 Elsevier Inc. All rights reserved.

Publication Date

12-1-2011

Publication Title

Journal of Inorganic Biochemistry

Volume

105

Issue

12

Number of Pages

1638-1644

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.jinorgbio.2011.08.002

Socpus ID

80355125253 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/80355125253

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