Unveiling the Unfolding Pathway of F5F8D Disorder-Associated D81H/V100D Mutant of MCFD2 via Multiple Molecular Dynamics Simulations

Combined factor deficiency (F5F8D) is a rare autosomal recessive disorder caused by mutations in the LMAN1 or MCFD2 genes. It has been proposed that this pathogenic process occurs via a multi-step pathway involving metal loss, EF-hand-Ca21 dissociation and assembly of misfolded MCFD2-LMAN1 complex. Here, we have investigated the solution conformations of the MCFD2(D81H,V100D) protein mutant through extensive molecular dynamics (MD) simulations. The V100D, one of the many MCFD2 mutations known to be associated to F5F8D, is difficult to be reconciled with the pathway model because it is located far from the metal sites and the MCFD2/LMAN1 interface. Consequently, an inspection of all the steps involved in D81H/V100D MCFD2 misfolding is expected to provide hints in the understanding of the molecular basis of the disease. A comparison with parallel studies carried out for the Wild-Type (WT) MCFD2 pointed out that the mutation decreases the affinity of the protein for the Ca21 ion. Multiple explicit solvents MD simulations (50 ns) performed on the two proteins revealed that in the WT protein, stable H-bond network and compact hydrophobic core region are created thus confirming a pivotal role of this region in driving the biophysical properties of the entire protein. In fact it is shown that the V100D mutation, although located far away the EF-hand domain, may induce subtle modification in the structural core of MCFD2 leading to the loosening of metal binding and to the formation of metastable intermediate states along the unfolding pathway. The native-like hydrophobic cluster formed near the V100 residue in the wild-type protein is disrupted by the negatively charged Asparagine residue. Furthermore, the presence of the D81H mutation in the EF-1 hand domain may also increase the protein unfolding rate and consequently prevent the formation of the MCFD2-LMAN1 complex. The detailed structural insights obtained from our large-scale simulations complement the clinical features and offer useful insights into the mechanism behind MCFD2 protein misfolding.

Key words: Molecular Dynamics; Mutations; Misfolding; F5F8D; LMAN1; MCFD2.

This article can be cited as:
A. Hamza, N-N. Wei, T. Johnson-Scallse, F. Naftolin, H. Cho, C-G. Zhan. Unveiling the Unfolding Pathway of F5F8D Disorder-Associated D81H/V100D Mutant of MCFD2 via Multiple Molecular Dynamics Simulations J. Biomol Struct Dyn 29(4), 699-714 (2012).

Adel Hamza1†*
Ning-Ning Wei1†2
Trudy Johnson-Scalise3
Frederick Naftolin4
Hoon Cho5*
Chang-Guo Zhan1*

1Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, Kentucky 40536
2State Key Laboratory of Fine Chemicals, School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China
3Laboratory of Neuro-Immuno- Endocrinology, Department of Physiology and Biochemistry, Szent Istvan University, Budapest, Hungary
4Department of Obstetrics and Gynecology, New York University Medical Center, New York, New York
5Department of Polymer Science & Engineering, Chosun University, Gwangju 501-759, South Korea
These authors contributed equally to this work.

*Corresponding authors:
Dr. Adel Hamza
Dr. Chang-Guo Zhan
Dr. Hoon Cho
Phone: 859-323-3943
Fax: 859-323-3575
E-mail: ahamz3@uky.edu

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