Interaction between succinyl CoA synthetase and the heme-biosynthetic enzyme ALAS-E is disrupted in sideroblastic anemia.

The first and the rate-limiting enzyme of heme biosynthesis is delta-aminolevulinate synthase (ALAS), which is localized in mitochondria. There are 2 tissue-specific isoforms of ALAS, erythroid-specific (ALAS-E) and nonspecific ALAS (ALAS-N). To identify possible mitochondrial factors that modulate ALAS-E function, we screened a human bone marrow cDNA library, using the ...
mitochondrial form of human ALAS-E as a bait protein in the yeast 2-hybrid system. Our screening led to the isolation of the beta subunit of human ATP-specific succinyl CoA synthetase (SCS-betaA). Using transient expression and coimmunoprecipitation, we verified that mitochodrially expressed SCS-betaA associates specifically with ALAS-E and not with ALAS-N. Furthermore, the ALAS-E mutants R411C and M426V associated with SCS-betaA, but the D190V mutant did not. Because the D190V mutant was identified in a patient with pyridoxine-refractory X-linked sideroblastic anemia, our findings suggest that appropriate association of SCS-betaA and ALAS-E promotes efficient use of succinyl CoA by ALAS-E or helps translocate ALAS-E into mitochondria.
Mesh Terms:
5-Aminolevulinate Synthetase, Acyl Coenzyme A, Adenosine Triphosphate, Amino Acid Sequence, Anemia, Sideroblastic, Animals, Base Sequence, Bone Marrow, CHO Cells, Cricetinae, Cricetulus, DNA, Complementary, Enzyme Induction, Erythroid Precursor Cells, Heme, Humans, Isoenzymes, Macromolecular Substances, Mitochondria, Heart, Molecular Sequence Data, Myocardium, Point Mutation, RNA, Messenger, Succinate-CoA Ligases, Two-Hybrid System Techniques
J. Clin. Invest.
Date: Mar. 01, 2000
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