Branched late-steps of the cytosolic iron-sulphur cluster assembly machinery of Trypanosoma brucei
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Fe-S clusters are ubiquitous cofactors of proteins involved in a variety of essential cellular processes. The biogenesis of Fe-S clusters in the cytosol and their insertion into proteins is accomplished through the cytosolic iron-sulphur protein assembly (CIA) machinery. The early- and middle-acting modules of the CIA pathway concerned with the assembly and trafficking of Fe-S clusters have been previously characterised in the parasitic protist Trypanosoma brucei. In this study, we applied proteomic and genetic approaches to gain insights into the network of protein-protein interactions of the late-acting CIA targeting complex in T. brucei. All components of the canonical CIA machinery are present in T. brucei including, as in humans, two distinct CIA2 homologues TbCIA2A and TbCIA2B. These two proteins are found interacting with TbCIA1, yet the interaction is mutually exclusive, as determined by mass spectrometry. Ablation of most of the components of the CIA targeting complex by RNAi led to impaired cell growth in vitro, with the exception of TbCIA2A in procyclic form (PCF) trypanosomes. Depletion of the CIA-targeting complex was accompanied by reduced levels of protein-bound cytosolic iron and decreased activity of an Fe-S dependent enzyme in PCF trypanosomes. We demonstrate that the C-terminal domain of TbMMS19 acts as a docking site for TbCIA2B and TbCIA1, forming a trimeric complex that also interacts with target Fe-S apo-proteins and the middle-acting CIA component TbNAR1.
Tonini , M L , Peña-Diaz , P , Haindrich , A C , Basu , S , Kriegová , E , Pierik , A J , Lill , R , MacNeill , S A , Smith , T K & Lukeš , J 2018 , ' Branched late-steps of the cytosolic iron-sulphur cluster assembly machinery of Trypanosoma brucei ' , PLoS Pathogens , vol. 14 , no. 10 , e1007326 . https://doi.org/10.1371/journal.ppat.1007326
Copyright: © 2018 Tonini et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
DescriptionSupport from the Czech Grant Agency (16-18699S to JL) and partial funding by CAPES/Science without Borders (BEX1333/13-5 to MLT) is kindly acknowledged. We are grateful to the University of St. Andrews mass spectrometry facility for collecting and processing MS data and to other members of the TKS and SM groups for their assistance with this project. Work of RL and AJP was supported by the Deutsche Forschungsgemeinschaft (Koselleck grant (to RL) and SPP 1927) and a Coordenação de aperfeiçoamento de pessoal de nivel superior (CAPES - 1333/2013-05) for the financial support to this project. We acknowledge networking support from the COST Action FeSBioNet (Contract CA15133). ERD Funds, The Czech Ministry of Education, project OPVVV 16_019/0000759 to JL.
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