Cryptic proteolytic activity of dihydrolipoamide dehydrogenase

Ngolela Esther Babady, Yuan Ping Pang, Orly Elpeleg, Grazia Isaya

Research output: Contribution to journalArticlepeer-review

76 Scopus citations


The mitochondrial enzyme, dihydrolipoamide dehydrogenase (DLD), is essential for energy metabolism across eukaryotes. Here, conditions known to destabilize the DLD homodimer enabled the mouse, pig, or human enzyme to function as a protease. A catalytic dyad (S456-E431) buried at the homodimer interface was identified. Serine protease inhibitors and an S456A or an E431A point mutation abolished the proteolytic activity, whereas other point mutations at the homodimer interface domain enhanced the proteolytic activity, causing partial or complete loss of DLD activity. In humans, mutations in the DLD homodimer interface have been linked to an atypical form of DLD deficiency. These findings reveal a previously unrecognized mechanism by which certain DLD mutations can simultaneously induce the loss of a primary metabolic activity and the gain of a moonlighting proteolytic activity. The latter could contribute to the metabolic derangement associated with DLD deficiency and represent a target for therapies of this condition.

Original languageEnglish (US)
Pages (from-to)6158-6163
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number15
StatePublished - Apr 10 2007


  • Frataxin
  • Friedreich ataxia
  • Mitochondria
  • Moonlighting enzymes
  • Protease

ASJC Scopus subject areas

  • General


Dive into the research topics of 'Cryptic proteolytic activity of dihydrolipoamide dehydrogenase'. Together they form a unique fingerprint.

Cite this