Membrane-associated human tyrosinase is an enzymatically active monomeric glycoprotein

PLoS One. 2018 Jun 5;13(6):e0198247. doi: 10.1371/journal.pone.0198247. eCollection 2018.

Abstract

Human tyrosinase (hTyr) is a Type 1 membrane bound glycoenzyme that catalyzes the initial and rate-limiting steps of melanin production in the melanosome. Mutations in the Tyr gene are linked to oculocutaneous albinism type 1 (OCA1), an autosomal recessive disorder. Currently, the application of enzyme replacement therapy for a treatment of OCA1 is hampered by the absence of pure hTyr. Here, full-length hTyr (residues 1-529) was overexpressed in Trichoplusia ni larvae infected with a baculovirus, solubilized with detergent and purified using chromatography. Michaelis-Menten kinetics, enzymatic specific activity, and analytical ultracentrifugation were used to compare the hTyr in detergent with the soluble recombinant intra-melanosomal domain, hTyrCtr (residues 19-469). Active hTyr is monomeric in detergent micelles suggesting no stable interactions between protein molecules. Both, hTyr and hTyrCtr, exhibited similar enzymatic activity and ligand affinity in L-DOPA and L-Tyrosine reactions. In addition, expression in larvae is a scalable process that will allow high yield protein production. Thus, larval production of enzymatically active human tyrosinase potentially could be a useful tool in developing a cure for OCA1.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Albinism, Oculocutaneous / enzymology
  • Albinism, Oculocutaneous / genetics
  • Albinism, Oculocutaneous / therapy
  • Enzyme Replacement Therapy
  • Humans
  • Monophenol Monooxygenase / chemistry*
  • Monophenol Monooxygenase / genetics
  • Monophenol Monooxygenase / therapeutic use
  • Protein Domains
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / therapeutic use

Substances

  • Recombinant Proteins
  • Monophenol Monooxygenase