Two Proteases, Trypsin Domain-containing 1 (Tysnd1) and Peroxisomal Lon Protease (PsLon), Cooperatively Regulate Fatty Acid β-Oxidation in Peroxisomal Matrix

• Published in: The Journal of biological chemistry 2011-12, Vol.286 (52), p.44367-44379
• Main Authors: Okumoto, Kanji, Kametani, Yukari, Fujiki, Yukio
• Format: Article
• Language: English
• Subjects: AAA ATPase; Cell Biology; Cysteine Endopeptidases - genetics; Cysteine Endopeptidases - metabolism; Enzyme Precursors - genetics; Enzyme Precursors - metabolism; Fatty Acid Oxidation; Fatty Acids - genetics; Fatty Acids - metabolism; Gene Knockdown Techniques; HEK293 Cells; HeLa Cells; Humans; Lon Protease; Molecular Cell Biology; Oxidation-Reduction; Peroxisome Homeostasis; Peroxisomes; Peroxisomes - enzymology; Peroxisomes - genetics; Protease; Protein Quality Control; Protein Sorting Signals - physiology; Protein Structure, Tertiary; Proteolysis; Serine Endopeptidases; Serine Proteases - genetics; Serine Proteases - metabolism; Tysnd1; β-Oxidation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M111.285197

The molecular mechanisms underlying protein turnover and enzyme regulation in the peroxisomal matrix remain largely unknown. Trypsin domain-containing 1 (Tysnd1) and peroxisomal Lon protease (PsLon) are newly identified peroxisomal matrix proteins that harbor both a serine protease-like domain and a peroxisome-targeting signal 1 (PTS1) sequence. Tysnd1 processes several PTS1-containing proteins and cleaves N-terminal presequences from PTS2-containing protein precursors. Here we report that knockdown of Tysnd1, but not PsLon, resulted in accumulation of endogenous β-oxidation enzymes in their premature form. The protease activity of Tysnd1 was inactivated by intermolecular self-conversion of the 60-kDa form to 15- and 45-kDa chains, which were preferentially degraded by PsLon. Peroxisomal β-oxidation of a very long fatty acid was significantly decreased by knockdown of Tysnd1 and partially lowered by PsLon knockdown. Taken together, these data suggest that Tysnd1 is a key regulator of the peroxisomal β-oxidation pathway via proteolytic processing of β-oxidation enzymes. The proteolytic activity of oligomeric Tysnd1 is in turn controlled by self-cleavage of Tysnd1 and degradation of Tysnd1 cleavage products by PsLon. Tysnd1 and PsLon are newly identified peroxisomal matrix serine proteases. Tysnd1 inactivates its protease activity by self-conversion of the 60-kDa form to 15- and 45-kDa chains that are then degraded by PsLon. Tysnd1 regulates the peroxisomal fatty acid β-oxidation pathway via proteolytic processing of β-oxidation enzymes. Tysnd1 and PsLon cooperatively regulate fatty acid β-oxidation in peroxisomal matrix. The data shed light on how enzyme turnover is regulated inside peroxisomes.