title: Ligation tunes protein reactivity in an ancient haemoglobin: kinetic evidence for an allosteric mechanism in Methanosarcina acetivorans protoglobin.
abstract: Protoglobin from Methanosarcina acetivorans (MaPgb) is a dimeric globin with peculiar structural properties such as a completely buried haem and two orthogonal tunnels connecting the distal cavity to the solvent. CO binding to and dissociation from MaPgb occur through a biphasic kinetics. We show that the heterogenous kinetics arises from binding to (and dissociation from) two tertiary conformations in ligation-dependent equilibrium. Ligation favours the species with high binding rate (and low dissociation rate). The equilibrium is shifted towards the species with low binding (and high dissociation) rates for the unliganded molecules. A quantitative model is proposed to describe the observed carbonylation kinetics.
authors.affiliation: Dipartimento di Fisica, Università degli Studi di Parma, Parma, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Abbruzzetti
authors.forename: Lesley
authors.initials: L
authors.lastname: Tilleman
authors.forename: Stefano
authors.initials: S
authors.lastname: Bruno
authors.forename: Cristiano
authors.initials: C
authors.lastname: Viappiani
authors.forename: Filip
authors.initials: F
authors.lastname: Desmet
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Doorslaer
authors.forename: Massimo
authors.initials: M
authors.lastname: Coletta
authors.forename: Chiara
authors.initials: C
authors.lastname: Ciaccio
authors.forename: Paolo
authors.initials: P
authors.lastname: Ascenzi
authors.forename: Marco
authors.initials: M
authors.lastname: Nardini
authors.forename: Martino
authors.initials: M
authors.lastname: Bolognesi
authors.forename: Luc
authors.initials: L
authors.lastname: Moens
authors.forename: Sylvia
authors.initials: S
authors.lastname: Dewilde
mesh_terms: D000494:Allosteric Regulation; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism; D005296:Ferrous Compounds / Q000737:chemistry / Q000378:metabolism; D005914:Globins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006454:Hemoglobins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D017020:Methanosarcina / Q000378:metabolism*; D010782:Photolysis; D011485:Protein Binding; D055503:Protein Multimerization; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D005296:Ferrous Compounds; D006454:Hemoglobins; D011994:Recombinant Proteins; D002248:Carbon Monoxide; D005914:Globins