puzzle picture
1915: Designable Linker: Coronavirus Spike Binder
Status: Closed


Name: 1915: Designable Linker: Coronavirus Spike Binder
Status: Closed
Created: 11/11/2020
Points: 100
Expired: 11/18/2020 - 23:00
Difficulty: Intermediate
Description: This is the second puzzle in the designable linker series! We are providing parts of two of the best-known designed binders to the SARS-CoV-2 spike, and are challenging players to link them together with a rigid linker! The two helical bundles are the parts of the two binders. They are currently connected with a flexible alanine linker that needs to be redesigned. We have also included the parts of the actual spike that are within 20 angstroms of the termini of the helices on the binders, so you know what regions your binder has to avoid to prevent clashing. The designable helices are a possible starting point for your linker designs.

Currently everything is frozen except for the linker and a portion of the helix on each binder. These residues are designable, and only residues on the linker and helices can be added and deleted. The two binder domains are held in place with strong constraints.

We have included a few objectives to help players generate well-folded designs. There are also some important differences between this and the first designable linker puzzle.

  1. The BUNS Filter is removed.
  2. The VAL helices are now treated like the linker, in that they are unconstrained, mutable, deletable and designable.
  3. The PDB is slightly different, and has much less clashing between residues on the spike and the binder.
  4. Because some spike residues are missing, the max linker length is slightly longer, since certain spike residues are no longer present.
It is a difficult problem to design a linker that can hold the binders in place. This type of puzzle is new for Foldit, and we are excited to see what players come up with!
Categories: Design, Overall

Top Groups

1Go Science36,545100
3Anthropic Dreams36,30956
5Void Crushers35,74829

Top Evolvers

Top Soloists

Need this puzzle? Log in to download.  


neilpg628's picture
User offline. Last seen 10 weeks 6 days ago. Offline
Joined: 08/01/2019
Groups: Foldit Staff

Residue Count (max +550)
Penalizes extra residues inserted beyond the starting 205, at a cost of 55 points per residue. Players may use up to 215 residues in total.

Core Existence (max +2400)
Ensures that at least 28 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.

SS Design (max +500)
Penalizes all CYS residues. Penalizes GLY, ALA residues in sheets. Penalizes GLY, ALA, SER, THR in helices.

Joined: 12/06/2008
Groups: Contenders

What was the reason for removing the BUNS filter? I thought a minimum number of BUNS was necessary for good core formation and a stable structure.

neilpg628's picture
User offline. Last seen 10 weeks 6 days ago. Offline
Joined: 08/01/2019
Groups: Foldit Staff

BUNS are more of an issue when designing interfaces between binders, because polar atoms are required at the interface to solubilize the monomers, but these polars need to make HBonds in the bound state. In this case, all buried atoms can be nonpolar since we only want the linker to fold. We have no bound and unbound states.

Joined: 06/24/2008
Groups: Void Crushers
Bug, maybe

MikeCassidyToday at 12:11 PM
Clicking on the Puzzle name in the App window is not opening up the puzzle in my www browser

grogar7's picture
User offline. Last seen 3 hours 26 min ago. Offline
Joined: 10/03/2011
Worked fine for me, Mike!

Worked fine for me, Mike! Windows 10, Microsoft Edge

agcohn821's picture
User offline. Last seen 2 days 20 hours ago. Offline
Joined: 11/05/2019
Groups: Foldit Staff

Hey Mike--is it working for you now?

Joined: 12/07/2007
Groups: Contenders
Peculiar wiggle

Wiggle is acting very strange on this pose (Linux/main). The score initially increases but then decreases to a value below the original. Seems unrelated to filters or wiggle power. Scientist-shared the offending pose as "bad wiggle 34896"

bkoep's picture
User offline. Last seen 21 hours 7 min ago. Offline
Joined: 11/15/2012
Groups: Foldit Staff
Blueprint Building Blocks

This looks related to Building Blocks that have been inserted into the Blueprint panel.

The Building Blocks add torsional constraints that try to push the backbone toward ideal phi/psi torsions. This helps to promote backbone patterns that are common in known protein structures, but these constraints (like rubber bands) can cause loss of points during Wiggle.

Joined: 12/07/2007
Groups: Contenders
tx bkoep: it's so easy to

tx bkoep: it's so easy to forget about those!

bkoep's picture
User offline. Last seen 21 hours 7 min ago. Offline
Joined: 11/15/2012
Groups: Foldit Staff

Yes, that's a problem that was never meant to persist. We had always planned to create a visual representation that shows Building Blocks on your solution, but it keeps getting pushed down the to-do list.

User login
Download links:
  Windows    OSX    Linux  
(10.12 or later)

Are you new to Foldit? Click here.

Are you a student? Click here.

Are you an educator? Click here.
Social Media

Only search fold.it
Other Games: Mozak
Recommend Foldit
Top New Users

Developed by: UW Center for Game Science, UW Institute for Protein Design, Northeastern University, Vanderbilt University Meiler Lab, UC Davis
Supported by: DARPA, NSF, NIH, HHMI, Amazon, Microsoft, Adobe, Boehringer Ingelheim, RosettaCommons