Glycosylation effects on FSH-FSHR interaction dynamics: a case study of different FSH glycoforms by molecular dynamics simulations

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Authors
Meher, Biswa Ranjan
Dixit, Anshuman
Bousfield, George R.
Lushington, Gerald H.
Advisors
Issue Date
2015-09-24
Type
Article
Keywords
Follicle-stimulating-hormone , In-vitro , Receptor , Roles , Water , Residues , Complex , Bbinding , Models , System
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Meher BR, Dixit A, Bousfield GR, Lushington GH (2015) Glycosylation Effects on FSH-FSHR Interaction Dynamics: A Case Study of Different FSH Glycoforms by Molecular Dynamics Simulations. PLoS ONE 10(9): e0137897
Abstract

The gonadotropin known as follicle-stimulating hormone (FSH) plays a key role in regulating reproductive processes. Physiologically active FSH is a glycoprotein that can accommodate glycans on up to four asparagine residues, including two sites in the FSH alpha subunit that are critical for biochemical function, plus two sites in the beta subunit, whose differential glycosylation states appear to correspond to physiologically distinct functions. Some degree of FSH beta hypo-glycosylation seems to confer advantages toward reproductive fertility of childbearing females. In order to identify possible mechanistic underpinnings for this physiological difference we have pursued computationally intensive molecular dynamics simulations on complexes between the high affinity site of the gonadal FSH receptor (FSHR) and several FSH glycoforms including fully-glycosylated (FSH24), hypo-glycosylated (e.g., FSH15), and completely deglycosylated FSH (dgFSH). These simulations suggest that deviations in FSH/FSHR binding profile as a function of glycosylation state are modest when FSH is adorned with only small glycans, such as single N-acetylglucosamine residues. However, substantial qualitative differences emerge between FSH15 and FSH24 when FSH is decorated with a much larger, tetra-antennary glycan. Specifically, the FSHR complex with hypo-glycosylated FSH15 is observed to undergo a significant conformational shift after 5-10 ns of simulation, indicating that FSH15 has greater conformational flexibility than FSH24 which may explain the more favorable FSH15 kinetic profile. FSH15 also exhibits a stronger binding free energy, due in large part to formation of closer and more persistent salt-bridges with FSHR.

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This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication
Publisher
Public Library of Science
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Series
PLoS ONE;v.10:no.9
PubMed ID
DOI
ISSN
1932-6203
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