S-Mercuration of rat sorbitol dehydrogenase by methylmercury causes its aggregation and the release of the zinc ion from the active site

Hironori Kanda, Takashi Toyama, Azusa Shinohara-Kanda, Akihiro Iwamatsu, Yasuhiro Shinkai, Toshiyuki Kaji, Makoto Kikushima, Yoshito Kumagai

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

We previously developed a screening method to identify proteins that undergo aggregation through S-mercuration by methylmercury (MeHg) and found that rat arginase I is a target protein for MeHg (Kanda et al. in Arch Toxicol 82:803-808, 2008). In the present study, we characterized another S-mercurated protein from a rat hepatic preparation that has a subunit mass of 42 kDa, thereby facilitating its aggregation. Two-dimensional SDS-polyacrylamide gel electrophoresis and subsequent peptide mass fingerprinting using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry revealed that the 42 kDa protein was NAD-dependent sorbitol dehydrogenase (SDH). With recombinant rat SDH, we found that MeHg is covalently bound to SDH through Cys44, Cys119, Cys129 and Cys164, resulting in the inhibition of its catalytic activity, release of zinc ions and facilitates protein aggregation. Mutation analysis indicated that Cys44, which ligates the active site zinc atom, and Cys129 play a crucial role in the MeHg-mediated aggregation of SDH. Pretreatment with the cofactor NAD, but not NADP or FAD, markedly prevented aggregation of SDH. Such a protective effect of NAD on the aggregation of SDH caused by MeHg is discussed.

Original languageEnglish
Pages (from-to)1693-1702
Number of pages10
JournalArchives of Toxicology
Volume86
Issue number11
DOIs
Publication statusPublished - 2012 Nov
Externally publishedYes

Keywords

  • Aggregation
  • Covalent modification
  • Cysteine
  • Methylmercury
  • Sorbitol dehydrogenase

ASJC Scopus subject areas

  • Toxicology
  • Health, Toxicology and Mutagenesis

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