Recognition of enzymes lacking bound cofactor by protein quality control

• Published in: Proceedings of the National Academy of Sciences - PNAS 2016-10, Vol.113 (43), p.12156-12161
• Main Authors: Martínez-Limón, Adrián, Alriquet, Marion, Lang, Wei-Han, Calloni, Giulia, Wittig, Ilka, Vabulas, R. Martin
• Format: Article
• Language: English
• Subjects: Animals; Biochemical analysis; Biochemistry; Biological Sciences; Coenzymes - chemistry; Coenzymes - deficiency; Enzymes; Flavoproteins - chemistry; Flavoproteins - genetics; Flavoproteins - metabolism; Gene Expression Profiling; Gene Expression Regulation; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; Maturation; Melanoma, Experimental; Mice; Models, Molecular; NAD - chemistry; NAD - metabolism; NAD(P)H Dehydrogenase (Quinone) - chemistry; NAD(P)H Dehydrogenase (Quinone) - genetics; NAD(P)H Dehydrogenase (Quinone) - metabolism; Peptides; Protein Aggregates; Protein Structure, Secondary; Protein synthesis; Proteolysis; Proteome - genetics; Proteome - metabolism; Proteomics; Proteomics - methods; Pyridoxal Phosphate - chemistry; Pyridoxal Phosphate - metabolism; Quality control; Riboflavin - chemistry; Riboflavin - metabolism; Thiamine Pyrophosphate - chemistry; Thiamine Pyrophosphate - metabolism; Tumor Cells, Cultured; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1611994113

Protein biogenesis is tightly linked to protein quality control (PQC). The role of PQC machinery in recognizing faulty polypeptides is becoming increasingly understood. Molecular chaperones and cytosolic and vacuolar degradation systems collaborate to detect, repair, or hydrolyze mutant, damaged, and mislocalized proteins. On the other hand, the contribution of PQC to cofactor binding-related enzyme maturation remains largely unexplored, although the loading of a cofactor represents an all-or-nothing transition in regard to the enzymatic function and thus must be surveyed carefully. Combining proteomics and biochemical analysis, we demonstrate here that cells are able to detect functionally immature wild-type enzymes. We show that PQC-dedicated ubiquitin ligase C-terminal Hsp70-interacting protein (CHIP) recognizes and marks for degradation not only a mutant protein but also its wild-type variant as long as the latter remains cofactor free. A distinct structural feature, the protruding C-terminal tail, which appears in both the mutant and wild-type polypeptides, contributes to recognition by CHIP. Our data suggest that relative insufficiency of apoprotein degradation caused by cofactor shortage can increase amyloidogenesis and aggravate protein aggregation disorders.