ISCA1 Orchestrates ISCA2 and NFU1 in the Maturation of Human Mitochondrial [4Fe-4S] Proteins. Issue 10 (14th May 2021)

• Record Type: Journal Article
• Authors: Suraci, Dafne; Saudino, Giovanni; Nasta, Veronica; Ciofi-Baffoni, Simone; Banci, Lucia
• Is Part Of: Journal of molecular biology. Volume 433:Issue 10(2021)
• Publication Date: 2021-05-14
• Subjects: iron-sulfur protein -- iron-sulfur cluster assembly machinery -- mitochondria -- NMR -- protein-protein interaction; Fe-S Iron-sulfur -- HSQC Heteronuclear single quantum coherence -- SEC-MALS Size exclusion chromatography equipped with multiangle light scattering -- LB Luria-Bertani -- IPTG Isopropyl-β-D-1-thiogalactopyranoside -- BSA Bovine serum albumin -- DTT 1, 4-dithiothreitol; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2021.166924
• Languages: English
• ISSNs: 0022-2836

Abstract

Graphical abstract: Highlights: ISCA1, ISCA2 and NFU1 are implicated in mitochondrial [4Fe-4S] protein biogenesis. ISCA1, interacting with ISCA2 and NFU1, promotes the formation of a ternary complex. ISCA2 and NFU1 do not interact with each other. The ternary complex coordinates a [4Fe-4S] 2+ cluster shared by ISCA1 and NFU1. ISCA1 has emerged as the key player of mitochondrial [4Fe-4S] protein biogenesis. Abstract: The late-acting steps of the pathway responsible for the maturation of mitochondrial [4Fe-4S] proteins are still elusive. Three proteins ISCA1, ISCA2 and NFU1 were shown to be implicated in the assembly of [4Fe-4S] clusters and their transfer into mitochondrial apo proteins. We present here a NMR-based study showing a detailed molecular model of the succession of events performed in a coordinated manner by ISCA1, ISCA2 and NFU1 to make [4Fe-4S] clusters available to mitochondrial apo proteins. We show that ISCA1 is the key player of the [4Fe-4S] protein maturation process because of its ability to interact with both NFU1 and ISCA2, which, instead do not interact each other. ISCA1 works as the promoter of the interaction between ISCA2 and NFU1 being able to determine the formation of a transient ISCA1-ISCA2-NFU1 ternary complex. We also show that ISCA1, thanks to its specific interaction with the C-terminal cluster-binding domain of NFU1, drives [4Fe-4S] cluster transfer from the site where the cluster is assembled on the ISCA1-ISCA2 complex to a cluster binding site formed by ISCA1 and NFU1 in the ternary ISCA1-ISCA2-NFU1 complex. Such mechanism guarantees that the [4Fe-4S] cluster can be safely moved from where it is assembled on the ISCA1-ISCA2 complex to NFU1, thereby resulting the [4Fe-4S] cluster available for the mitochondrial apo proteins specifically requiring NFU1 for their maturation.