Simultaneous depletion of Atm and Mdl rebalances cytosolic Fe-S cluster assembly but not heme import into the mitochondrion of Trypanosoma brucei.
ABC transporter mitochondrial 1 (Atm1) and multidrug resistance-like 1 (Mdl) are mitochondrial ABC transporters. Although Atm1 was recently suggested to transport different forms of glutathione from the mitochondrion, which are used for iron-sulfur (Fe-S) cluster maturation in the cytosol, the function of Mdl remains elusive. In Trypanosoma brucei, we identified one homolog of each of these genes, TbAtm and TbMdl, which were downregulated either separately or simultaneously using RNA interference. Individual depletion of TbAtm and TbMdl led to limited growth defects. In cells downregulated for TbAtm, the enzymatic activities of the Fe-S cluster proteins aconitase and fumarase significantly decreased in the cytosol but not in the mitochondrion. Downregulation of TbMdl did not cause any change in activities of the Fe-S proteins. Unexpectedly, the simultaneous downregulation of TbAtm and TbMdl did not result in any growth defect, nor were the Fe-S cluster protein activities altered in either the cytosolic or mitochondrial compartments. Additionally, TbAtm and TbMdl were able to partially restore the growth of the Saccharomyces cerevisiae Δatm1 and Δmdl2 null mutants, respectively. Because T. brucei completely lost the heme b biosynthesis pathway, this cofactor has to be obtained from the host. Based on our results, TbMdl is a candidate for mitochondrial import of heme b, which was markedly decreased in both TbMdl and TbAtm + TbMdl knockdowns. Moreover, the levels of heme a were strongly decreased in the same knockdowns, suggesting that TbMdl plays a key role in heme a biosynthesis, thus affecting the overall heme homeostasis in T. brucei.
Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.
Eva
E
Horáková
Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.|Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic.
Piya
P
Changmai
Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.
Zdeněk
Z
Paris
Institute of Medical Biochemistry Leopoldo de Meis, Centro de Ciências e da Saude, Federal University of Rio de Janeiro, Brazil.
Didier
D
Salmon
Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.|Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic.|Canadian Institute for Advanced Research, Toronto, Ontario, Canada.
Julius
J
Lukeš
D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000154:Aconitate Hydratase / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005649:Fumarate Hydratase / Q000378:metabolism; D055785:Gene Knockdown Techniques; D017125:Genes, Protozoan; D005816:Genetic Complementation Test; D006418:Heme / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000235:genetics / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D000154:Aconitate Hydratase; D005649:Fumarate Hydratase; D006418:Heme; D007506:Iron-Sulfur Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D015800:Protozoan Proteins
Atm; Fe-S cluster; Mdl; Trypanosoma; heme