title: Structural and functional characterization of an iron-sulfur cluster assembly scaffold protein-SufA from Plasmodium vivax.
abstract: Iron-sulfur (Fe-S) clusters are utilized as prosthetic groups in all living organisms for diverse range of cellular processes including electron transport in respiration and photosynthesis, sensing of ambient conditions, regulation of gene expression and catalysis. In Plasmodium, two Fe-S cluster biogenesis pathways are reported, of which the Suf pathway in the apicoplast has been shown essential for the erythrocytic stages of the parasite. While the initial components of this pathway detailing the sulfur mobilization have been elucidated, the components required for the assembly and transfer of Fe-S clusters are not reported from the parasite. In Escherichia coli, SufB acts as a scaffold protein and SufA traffics the assembled Fe-S cluster from SufB to target apo-proteins. However, in Plasmodium, the homologs of these proteins are yet to be characterized for their function. Here, we report a putative SufA protein from Plasmodium vivax with signature motifs of A-type scaffold proteins, which is evolutionarily conserved. The presence of the [Fe4S4](3+) cluster under reduced conditions was confirmed by UV-visible and EPR spectroscopy and the interaction of these clusters with the conserved cysteine residues of chains A and B of PvSufA, validates its existence as a dimer, similar to that in E. coli. The H-bond interactions at the PvSufA-SufB interface demonstrate SufA as a scaffold protein in conjunction with SufB for the pre-assembly of Fe-S clusters and their transfer to the target proteins. Co-localization of the protein to the apicoplast further provides an experimental evidence of a functional scaffold protein SufA for the biogenesis of Fe-S clusters in apicoplast of Plasmodium.
authors.affiliation: Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Rajasthan, India.
authors.forename: Zarna Rajeshkumar
authors.initials: ZR
authors.lastname: Pala
authors.affiliation: Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Rajasthan, India.
authors.forename: Vishal
authors.initials: V
authors.lastname: Saxena
authors.affiliation: Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Rajasthan, India.
authors.forename: Gagandeep Singh
authors.initials: GS
authors.lastname: Saggu
authors.affiliation: Department of Pharmacy, Birla Institute of Technology and Science, Pilani, Rajasthan, India.
authors.forename: Sushil Kumar
authors.initials: SK
authors.lastname: Yadav
authors.affiliation: Department of Pharmacy, Birla Institute of Technology and Science, Pilani, Rajasthan, India.
authors.forename: R P
authors.initials: RP
authors.lastname: Pareek
authors.affiliation: Department of Medicine, Sardar Patel Medical College, Bikaner, Rajasthan, India.
authors.forename: Sanjay Kumar
authors.initials: SK
authors.lastname: Kochar
authors.affiliation: Department of Medicine, Rajasthan University of Health Sciences, Jaipur, Rajasthan, India.
authors.forename: Dhanpat Kumar
authors.initials: DK
authors.lastname: Kochar
authors.affiliation: Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Rajasthan, India. Electronic address: shilpi@pilani.bits-pilani.ac.in.
authors.forename: Shilpi
authors.initials: S
authors.lastname: Garg
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D053898:Biosynthetic Pathways / Q000235:genetics; D002352:Carrier Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000378:metabolism; D006801:Humans; D007506:Iron-Sulfur Proteins / Q000235:genetics*; D008958:Models, Molecular; D010966:Plasmodium vivax / Q000235:genetics* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; C499169:SufA protein, E coli; C498860:SufB protein, E coli
keywords: Apicoplast; Clinical isolates; Immunofluorescence; Suf pathway