PMID:23589868

Citation	Nývltová, E, Šuták, R, Harant, K, Šedinová, M, Hrdy, I, Paces, J, Vlček, Č and Tachezy, J (2013) NIF-type iron-sulfur cluster assembly system is duplicated and distributed in the mitochondria and cytosol of Mastigamoeba balamuthi. Proc. Natl. Acad. Sci. U.S.A. 110:7371-6
Abstract	In most eukaryotes, the mitochondrion is the main organelle for the formation of iron-sulfur (FeS) clusters. This function is mediated through the iron-sulfur cluster assembly machinery, which was inherited from the α-proteobacterial ancestor of mitochondria. In Archamoebae, including pathogenic Entamoeba histolytica and free-living Mastigamoeba balamuthi, the complex iron-sulfur cluster machinery has been replaced by an ε-proteobacterial nitrogen fixation (NIF) system consisting of two components: NifS (cysteine desulfurase) and NifU (scaffold protein). However, the cellular localization of the NIF system and the involvement of mitochondria in archamoebal FeS assembly are controversial. Here, we show that the genes for both NIF components are duplicated within the M. balamuthi genome. One paralog of each protein contains an amino-terminal extension that targets proteins to mitochondria (NifS-M and NifU-M), and the second paralog lacks a targeting signal, thereby reflecting the cytosolic form of the NIF machinery (NifS-C and NifU-C). The dual localization of the NIF system corresponds to the presence of FeS proteins in both cellular compartments, including detectable hydrogenase activity in Mastigamoeba cytosol and mitochondria. In contrast, E. histolytica possesses only single genes encoding NifS and NifU, respectively, and there is no evidence for the presence of the NIF machinery in its reduced mitochondria. Thus, M. balamuthi is unique among eukaryotes in that its FeS cluster formation is mediated through two most likely independent NIF machineries present in two cellular compartments.
Links	PubMed PMC3645556 Online version:10.1073/pnas.1219590110
Keywords	Amino Acid Sequence; Amoeba/genetics; Amoeba/metabolism; Cytosol/metabolism; Entamoeba histolytica/metabolism; Gene Duplication; Iron-Sulfur Proteins/chemistry; Iron-Sulfur Proteins/genetics; Iron-Sulfur Proteins/metabolism; Mitochondria/metabolism; Molecular Sequence Data; Nitrogen Fixation/genetics; Protein Sorting Signals; Protein Transport; Saccharomyces cerevisiae/metabolism; Substrate Specificity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
MASBA:M9PAS4	part_of	GO:0005739: mitochondrion	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
MASBA:M9PAS4		GO:0005739: mitochondrion	ECO:0000314:		C		Fig. 3.	complete CACAO 8586

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