title: Reactive oxygen species regulates expression of iron-sulfur cluster assembly protein IscS of Leishmania donovani.
abstract: The cysteine desulfurase, IscS, is a highly conserved and essential component of the mitochondrial iron-sulfur cluster (ISC) system that serves as a sulfur donor for Fe-S clusters biogenesis. Fe-S clusters are versatile and labile cofactors of proteins that orchestrate a wide array of essential metabolic processes, such as energy generation and ribosome biogenesis. However, no information regarding the role of IscS or its regulation is available in Leishmania, an evolving pathogen model with rapidly developing drug resistance. In this study, we characterized LdIscS to investigate the ISC system in AmpB-sensitive vs resistant isolates of L. donovani and to understand its regulation. We observed an upregulated Fe-S protein activity in AmpB-resistant isolates but, in contrast to our expectations, LdIscS expression was upregulated in the sensitive strain. However, further investigations showed that LdIscS expression is positively correlated with ROS level and negatively correlated with Fe-S protein activity, independent of strain sensitivity. Thus, our results suggested that LdIscS expression is regulated by ROS level with Fe-S clusters/proteins acting as ROS sensors. Moreover, the direct evidence of a mechanism, in support of our results, is provided by dose-dependent induction of LdIscS-GFP as well as endogenous LdIscS in L. donovani promastigotes by three different ROS inducers: H2O2, menadione, and Amphotericin B. We postulate that LdIscS is upregulated for de novo synthesis or repair of ROS damaged Fe-S clusters. Our results reveal a novel mechanism for regulation of IscS expression that may help parasite survival under oxidative stress conditions encountered during infection of macrophages and suggest a cross talk between two seemingly unrelated metabolic pathways, the ISC system and redox metabolism in L. donovani.
authors: Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences, Agamkuan, Patna, India 800007.
authors: Krishn
authors: K
authors: Pratap Singh
authors: Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences, Agamkuan, Patna, India 800007.
authors: Amir
authors: A
authors: Zaidi
authors: Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences, Agamkuan, Patna, India 800007.
authors: Shadab
authors: S
authors: Anwar
authors: Department of Immunology, Rajendra Memorial Research Institute of Medical Sciences, Agamkuan, Patna, India 800007.
authors: Sanjeev
authors: S
authors: Bimal
authors: Department of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Agamkuan, Patna, India 800007.
authors: Pradeep
authors: P
authors: Das
authors: Laboratory of Molecular Biochemistry and Cell Biology, Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences, Agamkuan, Patna, India 800007. Electronic address: vahab_ali@yahoo.com.
authors: Vahab
authors: V
authors: Ali
mesh_terms: D000666:Amphotericin B / Q000494:pharmacology; D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology; D013437:Carbon-Sulfur Lyases / Q000096:biosynthesis*; D004351:Drug Resistance; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007506:Iron-Sulfur Proteins / Q000096:biosynthesis* / Q000378:metabolism; D007893:Leishmania donovani / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D008264:Macrophages / Q000469:parasitology; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D015800:Protozoan Proteins / Q000096:biosynthesis*; D011817:Rabbits; D015398:Signal Transduction; D024483:Vitamin K 3 / Q000494:pharmacology
chemical_list: D000981:Antiprotozoal Agents; D007506:Iron-Sulfur Proteins; D015800:Protozoan Proteins; D024483:Vitamin K 3; D000666:Amphotericin B; D006861:Hydrogen Peroxide; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase
keywords: Amphotericin B; Drug resistance; Iron–sulfur protein; Leishmania; Reactive oxygen species (ROS)