Experimental and bioinformatic investigation of the proteolytic degradation of the C-terminal domain of a fungal tyrosinase

G. Faccio (Corresponding Author), Mikko Arvas, L. Thöny-Meyer, Markku Saloheimo

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)

Abstract

Proteolytic processing is a key step in the production of polyphenol oxidases such as tyrosinases, converting the inactive proenzyme to an active form. In general, the fungal tyrosinase gene codes for a ~ 60 kDa protein that is, however, isolated as an active enzyme of ~ 40 kDa, lacking the C-terminal domain. Using the secreted tyrosinase 2 from Trichoderma reesei as a model protein, we performed a mutagenesis study of the residues in proximity of the experimentally determined cleavage site which are possibly involved in the proteolytic process. However, the mutant forms of tyrosinase 2 were not secreted in a full-length form retaining the C-terminal domain, but they were processed to give a ~ 45 kDa active form. Aiming at explaining this phenomenon, we analysed in silico the properties of the C-terminal domain of tyrosinase 2, of 23 previously retrieved homologous tyrosinase sequences from fungi (C. Gasparetti, G. Faccio, M. Arvas, J. Buchert, M. Saloheimo, K. Kruus, Appl. Microbiol. Biotechnol. 86 (2010) 213–226) and of nine well-characterised polyphenol oxidases. Based on the results of our study, we exclude the key role of specific amino acids at the cleavage site in the proteolytic process and report an overall higher sensitivity to proteolysis of the linker region and of the whole C-terminal domain of fungal tyrosinases.
Original languageEnglish
Pages (from-to)37-45
Number of pages9
JournalJournal of Inorganic Biochemistry
Volume121
DOIs
Publication statusPublished - 2013
MoE publication typeA1 Journal article-refereed

Keywords

  • c-terminal domain
  • fungal tyrosinase
  • protein processing
  • proteolytic activation
  • sensitivity to proteolysis

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