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.
Furuyama
K
K
Laboratory of Biochemical Hematology, The Rockefeller University, New York, New York 10021, USA.
Sassa
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D000624:5-Aminolevulinate Synthetase / Q000235:genetics / Q000378:metabolism*; D000214:Acyl Coenzyme A / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000756:Anemia, Sideroblastic / Q000201:enzymology*; D000818:Animals; D001483:Base Sequence; D001853:Bone Marrow / Q000737:chemistry; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D018076:DNA, Complementary / Q000235:genetics; D004790:Enzyme Induction; D015672:Erythroid Precursor Cells / Q000201:enzymology; D006418:Heme / Q000096:biosynthesis*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D008929:Mitochondria, Heart / Q000201:enzymology; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry; D017354:Point Mutation; D012333:RNA, Messenger / Q000096:biosynthesis; D013389:Succinate-CoA Ligases / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D000214:Acyl Coenzyme A; D018076:DNA, Complementary; D007527:Isoenzymes; D046911:Macromolecular Substances; D012333:RNA, Messenger; D006418:Heme; D000255:Adenosine Triphosphate; C012046:succinyl-coenzyme A; D000624:5-Aminolevulinate Synthetase; D013389:Succinate-CoA Ligases; C518788:SUCLA2 protein, human