Thioredoxin Txnl1/TRP32 Is a Redox-active Cofactor of the 26 S Proteasome

Katrine M. Andersen, Louise Madsen, Soren Prag, Anders H. Johnsen, Colin A. Semple, Klavs B. Hendil, Rasmus Hartmann-Petersen

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The 26 S proteasome is a large proteolytic machine, which degrades most intracellular proteins. We found that thioredoxin, Txnl1/TRP32, binds to Rpn11, a subunit of the regulatory complex of the human 26 S proteasome. Txnl1 is abundant, metabolically stable, and widely expressed and is present in the cytoplasm and nucleus. Txnl1 has thioredoxin activity with a redox potential of about -250 mV. Mutant Txnl1 with one active site cysteine replaced by serine formed disulfide bonds to eEF1A1, a substrate-recruiting factor of the 26 S proteasome. eEF1A1 is therefore a likely physiological substrate. In response to knockdown of Txnl1, ubiquitin-protein conjugates were moderately stabilized. Hence, Txnl1 is the first example of a direct connection between protein reduction and proteolysis, two major intracellular protein quality control mechanisms.
Original languageEnglish
Pages (from-to)15246-15254
Number of pages9
JournalJournal of Biological Chemistry
Volume284
Issue number22
DOIs
Publication statusPublished - 29 May 2009

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