Research

What we do

Our research lies in the field of classical simulation of biomolecular systems as well as biomimetic and synthetic nanomaterials. We develop hierarchical simulation approaches that systematically link models at several levels of resolution, for example combining an all-atom and a coarse-grained description. With such a multiscale approach we can address processes that require both chemical specificity as well as the sampling of long time and large length scales. In combination with ever-increasing computational power, these methods generate huge non-linear, high-dimensional datasets. Thus we employ concepts ranging from machine learning to network theory to extract information about structure and dynamics from these data.

Combining modern sampling and analysis methods, we investigate problems such as peptide folding, ligand binding, protein-membrane interactions, multi-domain systems, nanoparticle formation…


Current projects

EncoderMap

EncoderMap is our in-home developed tool for dimensionality reduction using a neural network autoencoder architecture. The newest release of EncoderMap comes with many quality of life improvements helping with featurization of MD data and introduces easy APIs to extend and customize the building, training, and reporting processes of the neural network. Find the documentation on: ag-peter.github.io/encodermap/index.html


Understanding biomolecules using network theory ​​​​​​​

Biomolecules are complex dynamic systems governed by the interactions within them. Network theory offers powerful tools to describe and understand these interactions. By integrating network theory with molecular simulations and machine learning we want to gain insight into complex biomolecular processes on multiple scales, both in space and time.


Ubiquitin and ubiquitin-like conjugates

The protein ubiquitin didn't get its name by chance. With roughly 5% of the human genome encoding ubiquitin-ligases and an outstanding evolutional conservation from yeast to humans, ubiquitin is truly everywhere. What's even more, ubiquitin has been found to play key roles in genetic and proteinic cellular processes. While ubiquitylation of certain substrate proteins dooms them for degradation by the 26S proteasome, ubiquitylation of DNA nucleoproteins can silence genes and regulate DNA accessibility.

Modeling chromatin structure

A cell's DNA is packed as a nucleoprotein complex compising the DNA and histone proteins. These proteins govern the compaction of the genetic material into chromatin fibers and chromosomes. Various post-translational modifications can be observed for these proteins. Especially the ubiquitylation of the linker histone H1 poses as a system of research interest for us.


Polymer Nanocrystals

In cooperation with experimentalists of the research group of Prof. Dr. Stefan Mecking, nanocrystals made out of functionalized polymers are simulated on atomistic and coarse-grained resolution levels. Of particular interest are formation, stability and appearance of those nanoparticles, and differences when utilizing different functional groups.


Riboswitches

Riboswitches reside in the 5′-UTRs of bacterial mRNAs and regulate gene expression upon interaction with small molecular ligands. We investigate ligand binding of a member of the guanidine sensing riboswitch family, the guanidine-II riboswitch (Gd-II) using extensive molecular dynamics simulations. 


Plasma membrane-localized deubiquitylating enzymes

 

Studying protein membrane partitioning/interaction and  its influence on the protein fold/function via molecular dynamic simulations at atomistic and coarse grained level.


Modeling of microtubule dynamics

Microtubules, the cytoskeleton filaments of cells are widely used as cancer therapeutics targets due to their vital role in the cell division process. Recent studies that use cryo-EM and computational modeling approaches provide new perspectives on the intricacies of microtubule dynamics. We aim to complement the emerging views by simulating microtubule systems on the coarse-grained level. 


Augmenting EPR Data

Unraveling mechanistics aspects of protein function by combined approaches of elctron resonance spectroscopy an computational chemistry (modeling, docking, MD).

  • Docking and MD studies are utilized to understand and visualize EPR-Data obtaned for ligands bound to Pyrrolysyl-tRNA Synthetase and develop a model for its alterating action.
  • Combination of computational approaches and EPR-distance measurements are used to understand the role of local folding and the interaction within the ribosome-associated complex. Here especially the ribosome associated chaperone Zuotin with the Ribosome.

Muscle Protein Kinases

​​​Specific protein kinases located in muscle fibers are postulated to act as mechanosensors. They are suggested to perceive the muscle sarcomere’s mechanical stretch and trigger signal pathways in response. To understand their mechanosensor activity, their conformational changes upon mechanical stretch need to be investigated. Multiscale molecular dynamics simulations are a promising tool in this regard, as they enable structural transformations to be studied on suitable time scales with atomistic resolution.


Other projects

Biominerals

Biominerals are known to exhibit outstanding properties. Different morphologies and different shapes arranged in superstructures allow for a great variety of properties. To fine-tune the morphology and control the characteristics of nanomaterials, an understanding of the response/influence of external factors (ionic strength, pH, etc.) at an atomistic-level is necessary. Many times, experimental techniques alone are not sufficient to obtain such fine details and classical atomistic MD, at times, is not suited due to time and length scale constraints. Therefore, we are utilizing multiscale simulation coarse-grained simulations and/or advanced sampling methods to understand the factors that control morphology in various biomineralization processes.

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Structural basis for functional differences between Ssa and Ssb chaperone

Chaperones are ubiquitous proteins that help other proteins undergo proper folding. Unlike other organisms, yeast have two distinct types of chaperones- the cytosolic Ssa and the ribosome-associated Ssb. Despite sequence and structural similarities, they function differently and the molecular basis of substrate specificity are poorly understood.

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Environment induced folding

Amphiphilic peptides respond to the presence of interfaces, pH-changes or other changes in the solution composition by conformational transitions. Atomistic simulation studies can accompany experiments from collaborators to understand the driving forces for different folds and folding transitions. We study how coarse grained models can be designed to reproduce such responses to environment changes.

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Intrinsically disordered systems

Intrinsically disordered proteins and peptides (IDPs) are biomolecules that lack well-defined secondary and tertiary structure. Several proteins that are considered intrinsically unstructured in solution such as α-synuclein, polyQ, τ-protein, and Aβ are involved in neurodegenerative diseases, such as Parkinson's disease and Alzheimer's syndrome. This is presumably due to their propensity for self-aggregation, fibril formation, but possibly also due to their interaction with biomembranes, often accompanied by conformational transitions.

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Peptide based nanomaterials: Morphology control

Development of new well ordered, functional biomaterials based on the underlying principal of self assembly has immense application in nanotechnology, nanomedicine and tissue engineering. Peptide based nanomaterials are not only biocompatible but also their properties can be altered easily by slight changes in environmental conditions and/or side chains of amino acids. We are doing multiscale simulation study on many interesting peptides systems that exhibit different morphologies upon slightly altering the primary sequence of peptides.

doi.org/10.1021/acs.jctc.8b01138

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Multiscale simulation of protein/lipid membrane systems

The aim of this project is to get a better understanding of the physical mechanisms of protein/protein and protein/lipid interactions im lipid membranes using multiscale simulations. The project is part of the Collaborative Research Center (SFB 625) in Mainz: "From Single Molecules to Nanoscopically Structured Materials". We want to study the aggregation of membrane proteins, in particular the light harvesting complex of green plants (LHC2b). We aim at a hierarchichal simulation approach where we connect high resolution models acting on the atomistic level with various levels of coarse grained models.

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SARS-CoV-2 Protease

Holology modeling and docking to support a ligand selection strategy for identification of chemical probes targeting the proteases of SARS-CoV-2.

doi.org/10.1002/anie.202016113

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Multiscale simulation of viral capsids

We use a combined approach of classical atomistic and different coarse grained (CG) simulation levels to investigate the 180-protein icosahedral capsid of Cowpea Chlorotic Mottle Virus (CCMV). The obtained model correctly predicts structural and elastic properties of bigger aggregates and mechanical properties of an entire virus capsid when compared to Atomic Force Microscopy experiment. Detailed analysis of the simulated rupture process allow us to propose an assembly model through well-defined oligomeric intermediate states, where the assembly order is regulated by the strengths of the interfacial binding, with a subsequent post-assembly reinforcement of weak spots by cooperative folding.

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