Issue 6, 2007

Molecular dynamics simulation of thermal unfolding of Thermatoga maritima DHFR

Abstract

Molecular dynamics simulations of the temperature-induced unfolding reaction of native dimeric dihydrofolate reductase from the hyperthermophile Thermatoga maritima (TmDHFR) and the experimentally inaccessible TmDHFR monomer were carried out at 400 K, 450 K and 500 K. The results revealed that the unfolding of TmDHFR subunits followed a similar path to that of the monomeric DHFR from the mesophile E. coli (EcDHFR). An initial collapse of the adenosine-binding domain (ABD) was followed by the loss of the N-terminal and loop domains (NDLD). Interestingly, the elements of the secondary structure of the isolated TmDHFR monomer were maintained for significantly longer periods of time for the hyperthermophilic enzyme, suggesting that subunit stability contributes to the enhanced resistance of TmDHFR to temperature-induced unfolding. The interactions between the subunits of the TmDHFR dimer led to a stabilisation of the NDLD. The hydrogen bonds between residues 140–143 in βG of one subunit and residues 125–127 in βF of the other subunit were retained for significant parts of the simulations at all temperatures. These intermolecular hydrogen bonds were lost after the unfolding of the individual subunits. The high stability of the dimer mediated by strong intersubunit contacts together with an intrinsically enhanced stability of the subunits compared to EcDHFR provides a molecular rational for the higher stability of the thermophilic enzyme. The computed unfolding pathways suggest that the partly folded dimer may be a genuine folding intermediate.

Graphical abstract: Molecular dynamics simulation of thermal unfolding of Thermatoga maritima DHFR

Supplementary files

Article information

Article type
Paper
Submitted
03 Aug 2006
Accepted
01 Dec 2006
First published
18 Dec 2006

Phys. Chem. Chem. Phys., 2007,9, 711-718

Molecular dynamics simulation of thermal unfolding of Thermatoga maritima DHFR

J. Pang and R. K. Allemann, Phys. Chem. Chem. Phys., 2007, 9, 711 DOI: 10.1039/B611210B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements