Antigen exposure leads to rigidification of germline antibody combining site

2014 ◽  
Vol 12 (03) ◽  
pp. 1450006 ◽  
Author(s):  
Jasmita Gill ◽  
Praapti Jayaswal ◽  
Dinakar M. Salunke
Keyword(s):  
Molecular Dynamics ◽  
Immune Complexes ◽  
Structural State ◽  
Bound States ◽  
Mechanistic Model ◽  
Conformational Transitions ◽  
Affinity Maturation ◽  
Antigen Binding ◽  
Dynamics Simulations ◽  
Antigen Release

Immune complexes involving diverse antigens and corresponding antibodies were analyzed for mapping conformational transitions of an antibody before antigen binding, upon antigen binding and after antigen release. Molecular dynamics simulations of the two comprehensive datasets consisting of the antigen-free and antigen-bound structures of the germline antibodies 36-65 and BBE6.12H3 provided mechanistic model of antigen encounter by primary antibodies. While native germline antibodies exhibit substantial mobility in the antigen-combining sites, their antigen-bound states exhibit relatively rigid conformations, even in the absence of the antigen suggesting preservation of the structural state after antigen release. It is proposed that acquired rigidity by a germline antibody upon antigen binding may be the first step in affinity maturation in favor of that antigen.

scholarly journals Antibodies exhibit multiple paratope states influencing VH–VL domain orientations

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Monica L. Fernández-Quintero ◽  
Nancy D. Pomarici ◽  
Barbara A. Math ◽  
Katharina B. Kroell ◽  
Franz Waibl ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Structural Information ◽  
Conformational Transitions ◽  
Antigen Binding ◽  
Antigen Binding Site ◽  
Solution Structures ◽  
Conformational Rearrangements ◽  
Complementarity Determining Regions ◽  
Dynamics Simulations

Abstract In the last decades, antibodies have emerged as one of the most important and successful classes of biopharmaceuticals. The highest variability and diversity of an antibody is concentrated on six hypervariable loops, also known as complementarity determining regions (CDRs) shaping the antigen-binding site, the paratope. Whereas it was assumed that certain sequences can only adopt a limited set of backbone conformations, in this study we present a kinetic classification of several paratope states in solution. Using molecular dynamics simulations in combination with experimental structural information we capture the involved conformational transitions between different canonical clusters and additional dominant solution structures occurring in the micro-to-millisecond timescale. Furthermore, we observe a strong correlation of CDR loop movements. Another important aspect when characterizing different paratope states is the relative VH/VL orientation and the influence of the distinct CDR loop states on the VH/VL interface. Conformational rearrangements of the CDR loops do not only have an effect on the relative VH/VL orientations, but also influence in some cases the elbow-angle dynamics and shift the respective distributions. Thus, our results show that antibodies exist as several interconverting paratope states, each contributing to the antibody’s properties.

scholarly journals Molecular dynamics simulations reveal distinct differences in conformational dynamics and thermodynamics between the unliganded and CD4-bound states of HIV-1 gp120

2020 ◽  
Vol 22 (10) ◽  
pp. 5548-5560
Author(s):  
Yi Li ◽  
Lei Deng ◽  
Jing Liang ◽  
Guang-Heng Dong ◽  
Yuan-Ling Xia ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Bound States ◽  
Conformational Dynamics ◽  
Immunological Properties ◽  
Dynamics Simulations ◽  
Hiv Gp120 ◽  
Hiv 1

Large changes in dynamics and thermodynamics of gp120 upon CD4 binding account for the functional and immunological properties of HIV/gp120.

scholarly journals Comment on ‘Valid molecular dynamics simulations of human hemoglobin require a surprisingly large box size’

2019 ◽  
Author(s):  
Vytautas Gapsys ◽  
Bert L. de Groot
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Size Dependence ◽  
Conformational Transitions ◽  
Human Hemoglobin ◽  
Order Of Magnitude ◽  
The Stability ◽  
Dynamics Simulations ◽  
T State

AbstractA recent molecular dynamics investigation into the stability of hemoglobin concluded that the unliganded protein is only stable in the T state when a solvent box is used in the simulations that is ten times larger than what is usually employed. Here, we express three main concerns about that study. In addition, we show that with an order of magnitude more statistics, the reported box size dependence is not reproducible. Overall, no significant effects on the kinetics or thermodynamics of conformational transitions were observed.

scholarly journals Comment on 'Valid molecular dynamics simulations of human hemoglobin require a surprisingly large box size'

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Vytautas Gapsys ◽  
Bert L de Groot
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Size Dependence ◽  
Conformational Transitions ◽  
Human Hemoglobin ◽  
Order Of Magnitude ◽  
The Stability ◽  
Dynamics Simulations ◽  
T State

A recent molecular dynamics investigation into the stability of hemoglobin concluded that the unliganded protein is only stable in the T state when a solvent box is used in the simulations that is ten times larger than what is usually employed (El Hage et al., 2018). Here, we express three main concerns about that study. In addition, we find that with an order of magnitude more statistics, the reported box size dependence is not reproducible. Overall, no significant effects on the kinetics or thermodynamics of conformational transitions were observed.

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