title: Anatomy of an iron-sulfur cluster scaffold protein: Understanding the determinants of [2Fe-2S] cluster stability on IscU.
abstract: Protein-bound iron sulfur clusters are prosthetic groups involved in several metabolic pathways. Understanding how they interact with the host protein and which factors influence their stability is therefore an important goal in biology. Here, we have addressed this question by studying the determinants of the 2Fe-2S cluster stability in the IscU/Isu protein scaffold. Through a detailed computational study based on a mixed quantum and classical mechanics approach, we predict that the simultaneous presence of two conserved residues, D39 and H105, has a conflicting role in cluster coordination which results in destabilizing cluster-loaded IscU/Isu according to a 'tug-of-war' mechanism. The effect is absent in the D39A mutant already known to host the cluster more stably. Our theoretical conclusions are directly supported by experimental data, also obtained from the H105A mutant, which has properties intermediate between the wild-type and the D39A mutant. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.
authors.affiliation: IUNICS, Departament de Química, Universitat de les Illes Balears, Crta. Valldemossa, km 7.5, E-07122 Palma de Mallorca, (Spain).
authors.forename: Miquel
authors.initials: M
authors.lastname: Adrover
authors.affiliation: Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy.
authors.forename: Barry D
authors.initials: BD
authors.lastname: Howes
authors.affiliation: Department of Biochemistry, Biophysics and General Pathology, Seconda Universita' di Napoli, Via De Crecchio 7, 80138 Naples, (Italy).
authors.forename: Clara
authors.initials: C
authors.lastname: Iannuzzi
authors.affiliation: Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy.
authors.forename: Giulietta
authors.initials: G
authors.lastname: Smulevich
authors.affiliation: Department of Clinical Neurosciences, King's College London, Denmark Hill Campus, London SE5, (UK). Electronic address: apastor@nimr.mrc.ac.uk.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Pastore
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020125:Mutation, Missense; D011485:Protein Binding; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013059:Spectrum Analysis, Raman
chemical_list: D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; C411665:IscU protein, E coli; D050505:Mutant Proteins
keywords: Iron–sulfur cluster; QM/MM methods; Scaffold protein; isc operon