Effects of Pressure on the Dynamics of an Oligomeric Protein from Deep-Sea Hyperthermophile

Published

November 10, 2015

Author(s)

Utsab R. Shrestha, Debsindhu Bhowmik, John R. Copley, Madhu Sudan Tyagi, Juscelino Leao, Xiang-Qiang Chu

Abstract

Inorganic Pyrophosphatase (IPPase) from Thermococcus thioreducens is a large oligomeric protein derived from a hyperthermophilic microorganism that is found near hydrothermal vents deep under the sea, where the pressure is up to 100 MPa (1 kbar). It has attracted great interest in biophysical research because of its high activity under extreme conditions in the seabed. In this study, we use the quasi-elastic neutron scattering (QENS) technique to investigate the effects of pressure on the conformational flexibility and relaxation dynamics of IPPase over a wide temperature range. The β-relaxation dynamics of proteins were studied in the time ranges from 2 to 25 picoseconds, and from 100 picosecions to 2 nanoseconds, using two spectrometers. Our results indicate that under a pressure of 100 MPa (1 kbar), close to that of the native environment deep under the sea, IPPase displays much faster relaxation dynamics than a mesophilic model protein, hen egg white lysozyme (HEWL) at all measured temperatures, opposite to what we observed previously under ambient pressure. This contradictory observation provides evidence that the protein energy landscape is distorted by high pressure, which is significantly different for hyperthermophilic (IPPase) and mesophilic (HEWL) proteins. We further derive from our observations a schematic denaturation phase diagram together with energy landscapes for the two very different proteins, which can be used as a general picture to understand the dynamical properties of thermophilic proteins under pressure.

Citation

Proceedings of the National Academy of Sciences of the United States of America

Volume

112

Issue

45

Pub Type

Journals

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Keywords

Dynamics, protein, pressure, neutron scattering

Citation

Shrestha, U. , Bhowmik, D. , Copley, J. , Tyagi, M. , Leao, J. and Chu, X. (2015), Effects of Pressure on the Dynamics of an Oligomeric Protein from Deep-Sea Hyperthermophile, Proceedings of the National Academy of Sciences of the United States of America, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=919097 (Accessed October 9, 2025)