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Mutational analysis of copper binding by human tyrosinase.

Abstract
Tyrosinase (EC 1.14.18.1) is a copper-containing enzyme that catalyzes several reactions in the biosynthesis of melanin pigments and is deficient in patients with type I oculocutaneous albinism (OCA1). Tyrosinase is thought to bind two copper ions, one at each of two conserved sequence motifs, termed CuA and CuB, but to date this has been directly proved only for the Neurospora and mushroom enzyme. Here, we demonstrate that mammalian tyrosinase directly binds copper, and that the CuA and CuB sites are both required for copper binding and for catalytic activity. We show that in human tyrosinase, copper binding by the CuB site is most likely coordinated by residues His363, His367, and His389, and that copper binding may be cooperative, with copper binding at one site facilitating copper binding by the other site. Furthermore, correct folding of the tyrosinase polypeptide appears to be necessary for copper binding, and a number of human OCA1 mutations disrupt copper binding and thus catalytic function of tyrosinase.
AuthorsR A Spritz, L Ho, M Furumura, V J Hearing Jr
JournalThe Journal of investigative dermatology (J Invest Dermatol) Vol. 109 Issue 2 Pg. 207-12 (Aug 1997) ISSN: 0022-202X [Print] United States
PMID9242509 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
Chemical References
  • Histidine
  • Copper
  • Monophenol Monooxygenase
Topics
  • Conserved Sequence
  • Copper (metabolism)
  • DNA Mutational Analysis
  • Histidine (genetics, physiology)
  • Humans
  • Monophenol Monooxygenase (genetics)
  • Mutation
  • Protein Binding (genetics)

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