Acyl carrier protein-specific 4'-phosphopantetheinyl transferase activates 10-formyltetrahydrofolate dehydrogenase.
4'-Phosphopantetheinyl transferases (PPTs) catalyze the transfer of 4'-phosphopantetheine (4-PP) from coenzyme A to a conserved serine residue of their protein substrates. In humans, the number of pathways utilizing the 4-PP post-translational modification is limited and may only require a single broad specificity PPT for all phosphopantetheinylation reactions. Recently, we have shown that one of the enzymes of folate metabolism, 10-formyltetrahydrofolate dehydrogenase (FDH), requires a 4-PP prosthetic group for catalysis. This moiety acts as a swinging arm to couple the activities of the two catalytic domains of FDH and allows the conversion of 10-formyltetrahydrofolate to tetrahydrofolate and CO2. In the current study, we demonstrate that the broad specificity human PPT converts apo-FDH to holoenzyme and thus activates FDH catalysis. Silencing PPT by small interfering RNA in A549 cells prevents FDH modification, indicating the lack of alternative enzymes capable of accomplishing this transferase reaction. Interestingly, PPT-silenced cells demonstrate significantly reduced proliferation and undergo strong G(1) arrest, suggesting that the enzymatic function of PPT is essential and nonredundant. Our study identifies human PPT as the FDH-modifying enzyme and supports the hypothesis that mammals utilize a single enzyme for all phosphopantetheinylation reactions.
Strickland
Kyle C
KC
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
Hoeferlin
L Alexis
LA
Oleinik
Natalia V
NV
Krupenko
Natalia I
NI
Krupenko
Sergey A
SA
D000213:Acyl Carrier Protein / Q000378:metabolism*; D001483:Base Sequence; D055162:Biocatalysis; D002453:Cell Cycle / Q000235:genetics; D016923:Cell Death / Q000235:genetics; D002460:Cell Line; D003001:Cloning, Molecular; D004789:Enzyme Activation; D020868:Gene Silencing; D006801:Humans; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry / Q000378:metabolism*; D010204:Pantetheine / Q000031:analogs & derivatives / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D012694:Serine / Q000378:metabolism; D013379:Substrate Specificity; D017855:Transferases (Other Substituted Phosphate Groups) / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000099295:Formyltetrahydrofolate Dehydrogenase
D000213:Acyl Carrier Protein; D000587:Oxidoreductases Acting on CH-NH Group Donors; D010204:Pantetheine; D034741:RNA, Small Interfering; D012694:Serine; D017855:Transferases (Other Substituted Phosphate Groups); D000099295:Formyltetrahydrofolate Dehydrogenase; C021364:holo-(acyl-carrier-protein) synthase; C003129:4'-phosphopantetheine