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1976: Influenza HA Binder Design: Round 5

Closed since over 1 year ago

Intermediate Overall Design


April 02, 2021
Max points

Design a protein to bind to influenza virus! This puzzle is set up just like Puzzle 1968. Although there is no competition this time for the players who submit the most solutions, you are still encouraged to restart the puzzle once you reach 10,000 points. The more designs we have to test, the better our chances at finding a successful binder for influenza HA!

The hemagglutinin (HA) protein is displayed on the surface of the influenza virus, where it can bind to receptors on human cells. Once the HA protein binds to a human receptor, the entire HA protein changes shape, springing open to trigger membrane fusion so that the virus can infect the human cell. We want to design a protein that can bind to the pre-fusion shape of HA, to stop it from springing open and thereby blocking infection.

In this puzzle, we've presented a section of the target HA protein in the pre-fusion shape. The backbone and most of the sidechains are frozen, except at the binding site, where flexible sidechains are shown in color. Players can design a new protein that can bind to these sidechains, stabilizing this pre-fusion shape. In order to bind the HA target, designs will need to make lots of hydrophobic contacts and satisfy any polar atoms that are buried at the interface. But designs will also need to have lots of secondary structure (helices or sheets) and a large core, so that they fold up correctly! Beware the large sugar sidechain next to the binding site, which has lots of polar atoms that can form unstable BUNS if you are not careful. See the puzzle comments for Objective details.

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bkoep Staff Lv 1

DDG Metric (max +2000)
The predicted binding energy of your design. The goal DDG is -40.0 or less.

Contact Surface Metric (max +2000)
Measures how much of your binder surface is in close contact with the target protein. The goal Contact Surface is 400 or more.

Buried Unsats (max +500)
Penalizes 100 points for each polar atom that cannot make any hydrogen bonds.

Core Existence (max +1500)
Ensures that at least 25 percent of residues are buried in the core of the monomer unit.

Interaction Energy (max +500)
Monitors that all large PHE, TYR, and TRP residues are scoring well.

Ideal Loops (max +500)
Penalizes any loop region that does not match one of the Building Blocks in the Blueprint tool. Use "Auto Structures" to see which regions of your protein count as loops.

SS Design (max +500)
Disabled use of CYS residues. Penalizes GLY, ALA residues in sheets and helices.