Large-Scale Recombinant Expression and Purification of Human Tyrosinase Suitable for Structural Studies

PLoS One. 2016 Aug 23;11(8):e0161697. doi: 10.1371/journal.pone.0161697. eCollection 2016.

Abstract

Human tyrosinase (TYR) is a glycoprotein that initiates the first two reactions in the melanin biosynthesis pathway. Mutations in its encoding gene cause Oculocutaneous Albinism type I (OCA1), the most severe form of albinism, which is a group of autosomal recessive disorders characterized by reduced or absent production of melanin in skin, hair and eyes. Despite extensive structural and characterization studies of its homologues in lower eukaryotic organisms, the catalytic mechanism of human TYR and the molecular basis of OCA1 are largely unknown. In this work, we have carried out a large-scale recombinant expression of TYR that has enabled us to obtain high yields of pure and active protein, required for crystallization trials and screening of skin whitening agents, which is highly demanded in the cosmetic industry. Addition of an N-terminal honeybee melittin signal peptide for secretion of the produced protein into the (protein-free) medium, as well as a cleavable His-tag at the C-terminus, was crucial for increasing the yield of pure protein. We have successfully crystallized two TYR variants, in both glycosylated and deglycosylated forms, showing preliminary X-ray diffraction patterns at 3.5 Å resolution. Hence, we have established an expression and purification protocol suitable for the crystal structure determination of human TYR, which will give unique atomic insight into the nature and conformation of the residues that shape the substrate binding pocket that will ultimately lead to efficient compound design.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Chromatography
  • Gene Expression
  • Glycosylation
  • Humans
  • Monophenol Monooxygenase / chemistry*
  • Monophenol Monooxygenase / genetics
  • Monophenol Monooxygenase / isolation & purification*
  • Monophenol Monooxygenase / metabolism
  • Protein Stability
  • Recombinant Proteins*
  • Structure-Activity Relationship
  • Temperature
  • X-Ray Diffraction

Substances

  • Recombinant Proteins
  • Monophenol Monooxygenase

Grants and funding

This research was funded by the ESRF and the Groningen Biomolecular Sciences and Biotechnology Institute (GBB) of the University of Groningen. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.