May 2025 - ChimeraX-users - RBVI Mailing Lists

Options to align two models and calculate per-residue RMSD
by christian.steinmetzger＠imbim.uu.se 07 May '25

07 May '25

Dear ChimeraX users, I'm working with some different ribosome structures which I first want to align to a reference structure (as rigid bodies) and then calculate RMSD values with respect to the reference. The number of chains are the same between my structures and the reference, and the chain names + residue numbers are congruent as well. However, some of my chains have residues missing or added at the ends, have a small number of insertions (using insertion codes in the pdb file) or point mutations. What I have tried so far is: "matchmaker #2 to #1 pairing ss show true" "save file.defattr #2 attrName r:seq_rmsd modelIds false" (to store the resulting RMSD values for later use) which aligns based on CA for protein chains and C4' for RNA. I haven't given any explicit chain specification (each model has 56 chains). Am I correct to think that the RMSD values I get are based on a whole-structure rigid-body alignment that takes all chains into account simultaneously? Or does it align each chain in #2 to its matching chain in #1 individually? For the proteins I think per-residue CA-RMSD values are suitable for what I need, but for the RNA chains I would like to get per-residue all-atom RMSDs, not just C4'. Can this be achieved with matchmaker? I have also tried to use the align command like this: "align #2 toAtoms #1 each structure matchChainIds true matchNumbering true" which, to my understanding, would do the alignment not just based on CA/C4', but for all atoms. Is that correct? With this, what would be the best way to extract per-residue RMSD values? The "rmsd" command rightfully complains about unequal numbers of atoms between #1 and #2. Is there a way to implicitly select only the atoms that are congruent between #1 and #2? Kind regards, Christian

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RMSD for all frames in a trajectory
by Alexandra Zahradnikova 07 May '25

07 May '25

Dear All, I am working with a trajectory of a tetramer. I would like to align the A chains in all frame of the trajectory and then calculate the rmsd of all chains in all frames relative to the respective chain of the first frame (i.e., align only chains A but calculate for all chains), and write the results to a text file. Is that possible? I can do a similar calculation with a script in old Chimera but don’t know how to do it in ChimeraX. I attach the zipped script for old Chimera. Best regards Sasha

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Re: [Chimera-users] Add sequence logo to view
by Elaine Meng 05 May '25

05 May '25

Hi Alex, Sorry no we do not have a feature like that currently. (P.S. It may be better to use the chimerax-users(a)cgl.ucsf.edu <mailto:chimerax-users@cgl.ucsf.edu> address CC'd here for ChimeraX questions.) In ChimeraX: The most similar thing I can thihk of is that for deep mutational scanning results it is possible to show labels with the scores of each residue type shown in a color-coded grid, but the "rub" is that you would have to open the data from a specific format we are using for these kinds of results: mutation scores format: <https://rbvi.ucsf.edu/chimerax/docs/user/formats/mutationcsv.html> I could imagine that instead the sequence alignment profile at each position could be shown as a similar label. ChimeraX has a new profile-grid viewer for sequence alignments as an optional alternative to the standard viewer, <https://rbvi.ucsf.edu/chimerax/docs/user/tools/profilegrid.html> .... so such a label could essentially be the profile column rearranged into a squarish grid, as in the mutational scanning labels image above. However, that has not yet been discussed (nor implemented, of course). We do not have any sequence logo type of display. Regards, Elaine ----- Elaine C. Meng, Ph.D. UCSF Chimera(X) team Resource for Biocomputing, Visualization, and Informatics Department of Pharmaceutical Chemistry University of California, San Francisco > On May 5, 2025, at 7:35 AM, Alexander Lee via Chimera-users <chimera-users(a)cgl.ucsf.edu> wrote: > > Dear ChimeraX community, > > I have a consensus sequence + logo done in an outside program. Is there a way to superimpose this onto a crystal structure? When hovering my mouse over a residue in the structure viewer (or sequence viewer), I would like the logo to come up. Is there a similar feature available? > > Regards, > Alex > _______________________________________________ > Chimera-users mailing list -- chimera-users(a)cgl.ucsf.edu > To unsubscribe send an email to chimera-users-leave(a)cgl.ucsf.edu > Archives: https://mail.cgl.ucsf.edu/mailman/archives/list/chimera-users@cgl.ucsf.edu/

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How can I overlay the 2Fo-Fc density map onto the amino acid residues I specified?
by 1025049892＠qq.com 04 May '25

04 May '25

Every time I open the map file in ChimeraX, I find that it doesn't overlap with my PDB structure. Why is this the case, and how can I make them match? Thank you for your attention. I'm looking forward to your reply.

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Morphing of structures with different chain numbers
by Enrico Martinez 01 May '25

01 May '25

Dear ChimeraX Users, I am trying to perform a morphing between two cryo-EM structures of the same complex, where one structure has twice the number of chains as the other (PDBs 3J9K and 8Y6Q). However, the larger structure causes an error during morphing. I have attempted to write a script that aligns the two structures and deletes the unmatched chains from the larger structure. Unfortunately, the script is not working as expected. from chimerax.core.commands import run def delete_unmatched_chains(session): # Get models #1 and #2 m1 = next((m for m in session.models if m.id == (1,)), None) m2 = next((m for m in session.models if m.id == (2,)), None) if m1 is None or m2 is None: session.logger.info("Model #1 or #2 not found.") return chains1 = {chain.chain_id for chain in m1.chains} chains2 = {chain.chain_id for chain in m2.chains} unmatched = chains1 - chains2 if unmatched: chain_ids = ",".join(unmatched) # Deleting unmatched chains run(session, f"delete /{chain_ids}") session.logger.info(f"Deleted chains: {', '.join(unmatched)}") else: session.logger.info("No unmatched chains found.") Could you please help me or alternatively propose another solution? Any suggestions would be greatly appreciated. Thank you in advance ! Enrico

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