A Trypanosomatid Iron Transporter that Regulates Mitochondrial Function Is Required for Leishmania amazonensis Virulence

PLoS Pathogens

Maria Fernanda Laranjeira-Silva¹  Norma W. Andrews¹  Bidyottam Mittra¹  Juliana Perrone Bezerra de Menezes¹  Vladimir Michailowsky¹  Jennifer Jensen² 

[1] Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, United States of America;Laboratório de Patologia e Biointervenção, CPqGM, FIOCRUZ, Candeal, Salvador, Bahia, Brazil

关键词: Mitochondria;    Promastigotes;    Amastigotes;    Parasitic diseases;    Leishmania;    Trypanosoma brucei gambiense;    Macrophages;    Respiratory infections;   

DOI  :  10.1371/journal.ppat.1005340

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Iron, an essential co-factor of respiratory chain proteins, is critical for mitochondrial function and maintenance of its redox balance. We previously reported a role for iron uptake in differentiation of Leishmania amazonensis into virulent amastigotes, by a mechanism that involves reactive oxygen species (ROS) production and is independent of the classical pH and temperature cues. Iron import into mitochondria was proposed to be essential for this process, but evidence supporting this hypothesis was lacking because the Leishmania mitochondrial iron transporter was unknown. Here we describe MIT1, a homolog of the mitochondrial iron importer genes mrs3 (yeast) and mitoferrin-1 (human) that is highly conserved among trypanosomatids. MIT1 expression was essential for the survival of Trypanosoma brucei procyclic but not bloodstream forms, which lack functional respiratory complexes. L. amazonensis LMIT1 null mutants could not be generated, suggesting that this mitochondrial iron importer is essential for promastigote viability. Promastigotes lacking one LMIT1 allele (LMIT1/Δlmit1) showed growth defects and were more susceptible to ROS toxicity, consistent with the role of iron as the essential co-factor of trypanosomatid mitochondrial superoxide dismutases. LMIT1/Δlmit1 metacyclic promastigotes were unable to replicate as intracellular amastigotes after infecting macrophages or cause cutaneous lesions in mice. When induced to differentiate axenically into amastigotes, LMIT1/Δlmit1 showed strong defects in iron content and function of mitochondria, were unable to upregulate the ROS-regulatory enzyme FeSOD, and showed mitochondrial changes suggestive of redox imbalance. Our results demonstrate the importance of mitochondrial iron uptake in trypanosomatid parasites, and highlight the role of LMIT1 in the iron-regulated process that orchestrates differentiation of L. amazonensis into infective amastigotes.

【 授权许可】

CC BY