Ligation tunes protein reactivity in an ancient haemoglobin: kinetic evidence for an allosteric mechanism in Methanosarcina acetivorans protoglobin.

PLoS ONE. 2012;7(3):e33614 DOI 10.1371/journal.pone.0033614

 

Journal Homepage

Journal Title: PLoS ONE

ISSN: 1932-6203 (Online)

Publisher: Public Library of Science (PLoS)

LCC Subject Category: Medicine | Science

Country of publisher: United States

Language of fulltext: English

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AUTHORS

Stefania Abbruzzetti
Lesley Tilleman
Stefano Bruno
Cristiano Viappiani
Filip Desmet
Sabine Van Doorslaer
Massimo Coletta
Chiara Ciaccio
Paolo Ascenzi
Marco Nardini
Martino Bolognesi
Luc Moens
Sylvia Dewilde

EDITORIAL INFORMATION

Peer review

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Time From Submission to Publication: 24 weeks

 

Abstract | Full Text

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.