Swiss-model

Key takeaways

Swiss-model belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Swiss-model to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Swiss-model from memory before moving on to harder problems.

Reference excerpt

Swiss-model (stylized as SWISS-MODEL) is a structural bioinformatics web-server dedicated to homology modeling of 3D protein structures. Before AlphaFold, homology modeling was the most accurate method to generate reliable three-dimensional protein structure models. To this day, it is still used in many practical applications where deep learning techniques fall short because of their data-driven approach. Homology (or comparative) modelling methods make use of experimental protein structures (templates) to build models for evolutionary related proteins (targets). Today, Swiss-model consists of three tightly integrated components: (1) The Swiss-model pipeline – a suite of software tools and databases for automated protein structure modelling, (2) The Swiss-model Workspace – a web-based graphical user interface workbench, (3) The Swiss-model Repository – a continuously updated database of homology models for a set of model organism proteomes of high biomedical interest.

Pipeline Swiss-model pipeline comprises the four main steps that are involved in building a homology model of a given protein structure:

Identify structural template(s). BLAST and HHblits are used to identify templates. Those are stored in the Swiss-model Template Library (SMTL), which is derived from Protein Data Bank (PDB). Align target sequence and template structure(s). Build model and minimize energy. Swiss-model implements a rigid fragment assembly approach in modelling. Assess model quality using QMEAN, a statistical potential of mean force.

Workspace The Swiss-model Workspace integrates programs and databases required for protein structure prediction and modelling in a web-based workspace. Depending on the complexity of the modelling task, different modes of use can be applied, in which the user has different levels of control over individual modelling steps: automated mode, alignment mode, and project mode. A fully automated mode is used when a sufficiently high sequence identity between target and template (>50%) allows for no human intervention at all. In this case only the sequence or UniProt accession code of the protein is required as input. The alignment mode enables the user to input their own target-template alignments from which the modelling procedure starts (i.e. search for templates step is skipped and rarely only minor changes in the provided alignment are made). The project mode is used in more difficult cases, when manual corrections of target-template alignments are needed to improve the quality of the resulting model. In this mode the input is a project file that can be generated by the DeepView (Swiss Pdb Viewer) visualization and structural analysis tool, to allow the user to examine and manipulate the target-template alignment in its structural context. In all three cases the output is a pdb file with atom coordinates of the model or a DeepView project file. The four main steps of homology modelling may be repeated iteratively until a satisfactory model is achieved. The Swiss-model Workspace is accessible via the ExPASy web server, or it can be used as part of the program DeepView (Swiss Pdb-Viewer). As of September 2015 it has been cited 20000 times in scientific literature, making it one of the most widely used tools for protein structure modelling. The tool is free for academic use.

Repository The Swiss-model Repository provides access to an up-to-date collection of annotated three-dimensional protein models for a set of model organisms of high general interest. Model organisms include human, mouse, C.elegans, E.coli, and various pathogens including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Swiss-model Repository is integrated with several external resources, such as UniProt, InterPro, STRING, and Nature Protein Structure Initiative (PSI) SBKB. New developments of the Swiss-model expert system feature (1) automated modelling of homo-oligomeric assemblies; (2) modelling of essential metal ions and biologically relevant ligands in protein structures; (3) local (per-residue) model reliability estimates based on the QMEAN local score function; (4) mapping of UniProt features to models. (1) and (2) are available when using the automated mode of the Swiss-model Workspace; (3) is always provided when calculating an homology model using the Swiss-model Workspace, and (4) is available in the Swiss-model Repository.

Accuracy and reliability of the method In the past, the accuracy, stability and reliability of the Swiss-model server pipeline was validated by the EVA-CM benchmark project. As of 2024, the Swiss-model server pipeline is participating in the Continuous Automated Model EvaluatiOn (CAMEO3D) project, which continuously evaluates the accuracy and reliability of protein structure prediction services via fully automated means.

References

External links Official website

See also Homology modelling Protein structure prediction Protein structure prediction software CASP (Critical Assessment of Techniques for Protein Structure Prediction)

Worked examples

Example 1 — a first encounter with Swiss-model

Start with the simplest possible case. Write down what Swiss-model claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Swiss-model before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Swiss-model ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Swiss-model

In research: Swiss-model appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Swiss-model in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Swiss-model is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bioinformatics, Molecular modelling software, so understanding it makes those chapters shorter.
In everyday life: Look for Swiss-model outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Swiss-model in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Swiss-model means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Swiss-model out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Swiss-model in simple terms?

Swiss-model (stylized as SWISS-MODEL) is a structural bioinformatics web-server dedicated to homology modeling of 3D protein structures. Before AlphaFold, homology modeling was the most accurate method to generate reliable three-dimensional protein structure models.

Why does Swiss-model matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Swiss-model?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Swiss-model.