PUBLICATION
The ubiquitous mitochondrial protein unfoldase CLPX regulates erythroid heme synthesis by control of iron utilization and heme synthesis enzyme activation and turnover
- Authors
- Rondelli, C.M., Perfetto, M., Danoff, A., Bergonia, H., Gillis, S., O'Neill, L., Jackson, L., Nicolas, G., Puy, H., West, R., Phillips, J.D., Yien, Y.Y.
- ID
- ZDB-PUB-211216-19
- Date
- 2021
- Source
- The Journal of biological chemistry 297: 100972 (Journal)
- Registered Authors
- Keywords
- 5-aminolevulinate synthase, ATP-dependent protease, ferrochelatase, heme, iron, mitochondria, porphyria, protein degradation, protoporphyrinogen IX oxidase
- MeSH Terms
-
- 5-Aminolevulinate Synthetase/metabolism*
- Animals
- Cell Line, Tumor
- Endopeptidase Clp/genetics
- Endopeptidase Clp/metabolism*
- Enzyme Activation
- Ferrochelatase/metabolism*
- Gene Knockout Techniques/methods
- Heme/biosynthesis*
- Iron/metabolism*
- Leukemia, Erythroblastic, Acute/enzymology
- Leukemia, Erythroblastic, Acute/genetics
- Leukemia, Erythroblastic, Acute/pathology*
- Mice
- Mitochondria/metabolism*
- Models, Animal
- Proteolysis
- Zebrafish
- PubMed
- 34280433 Full text @ J. Biol. Chem.
Citation
Rondelli, C.M., Perfetto, M., Danoff, A., Bergonia, H., Gillis, S., O'Neill, L., Jackson, L., Nicolas, G., Puy, H., West, R., Phillips, J.D., Yien, Y.Y. (2021) The ubiquitous mitochondrial protein unfoldase CLPX regulates erythroid heme synthesis by control of iron utilization and heme synthesis enzyme activation and turnover. The Journal of biological chemistry. 297:100972.
Abstract
Heme plays a critical role in catalyzing life-essential redox reactions in all cells, and its synthesis must be tightly balanced with cellular requirements. Heme synthesis in eukaryotes is tightly regulated by the mitochondrial AAA+ unfoldase CLPX (caseinolytic mitochondrial matrix peptidase chaperone subunit X), which promotes heme synthesis by activation of δ-aminolevulinate synthase (ALAS/Hem1) in yeast and regulates turnover of ALAS1 in human cells. However, the specific mechanisms by which CLPX regulates heme synthesis are unclear. In this study, we interrogated the mechanisms by which CLPX regulates heme synthesis in erythroid cells. Quantitation of enzyme activity and protein degradation showed that ALAS2 stability and activity were both increased in the absence of CLPX, suggesting that CLPX primarily regulates ALAS2 by control of its turnover, rather than its activation. However, we also showed that CLPX is required for PPOX (protoporphyrinogen IX oxidase) activity and maintenance of FECH (ferrochelatase) levels, which are the terminal enzymes in heme synthesis, likely accounting for the heme deficiency and porphyrin accumulation observed in Clpx-/- cells. Lastly, CLPX is required for iron utilization for hemoglobin synthesis during erythroid differentiation. Collectively, our data show that the role of CLPX in yeast ALAS/Hem1 activation is not conserved in vertebrates as vertebrates rely on CLPX to regulate ALAS turnover as well as PPOX and FECH activity. Our studies reveal that CLPX mutations may cause anemia and porphyria via dysregulation of ALAS, FECH, and PPOX activities, as well as of iron metabolism.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping