Replacement of the axial copper ligand methionine with lysine in amicyanin converts it to a zinc-binding protein that no longer binds copper

Journal Article · Wed Jul 11 04:00:00 EDT 2012 · J. Inorg. Biochem.

DOI:https://doi.org/10.1016/j.jinorgbio.2011.08.002· OSTI ID:1039454

Sukumara, Narayanasami; Choib, Moonsung; Davidson, Victor L ^[1]

---

1. Central Florida

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{sup 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{sup 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.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE Office of Science (SC)
• OSTI ID: 1039454
• Journal Information: J. Inorg. Biochem., Journal Name: J. Inorg. Biochem. Journal Issue: (12) ; 12, 2011 Vol. 105; ISSN JIBIDJ; ISSN 0162-0134
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

08 HYDROGEN
ABSORPTION
AFFINITY
BINDING ENERGY
COPPER
CRYSTAL STRUCTURE
ELECTRONS
HYDROGEN
LYSINE
METHIONINE
METHYLAMINE
MUTATIONS
OXIDOREDUCTASES
PRECIPITATION
PROTEINS
VALENCE
WATER
ZINC