- ChimeraX-users - RBVI Mailing Lists

how to build N-linked glycans
by Alexis Rohou 09 Nov '23

09 Nov '23

Hi there, How would you recommend I go about building an N-linked glycan chain off of an ASN in an existing model using ChimeraX or ISOLDE? Is there documentation on this somewhere? Cheers, Alexis

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Custom calculation of forcefields for ligands in Isolde
by Paul Sauer 09 Nov '23

09 Nov '23

Dear ChimeraX and Isolde experts, I am trying to parameterize a ligand in Isolde 1.6 in order to fit it into my density. The ligand conforms to the requirements that are outlined in the manual (not covalently bound, only consists of certain elements, etc). However, parameterizing the residue using the inbuilt ANTECHAMBER/AMBER utility times out unfortunately, with an error saying that convergence in SCF cannot be reached. Upon investigating the issue I learned that it could be possible to avoid this error with adjusted command line parameters for AMBER in order to let it run longer for correct values. My question is: Is it possible to pass custom flags or command line arguments from Isolde to AMBER in ChimeraX? And if yes, how? The default command ‘Isolde parameterize residue’ does not seem to have any AMBER specific options. For example, how can I add 'adding ndiis_attempts=700’ (or other modifications) to my input sqm file? Thank you in advance, Paul

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How to refine a symmetric model with ISOLDE
by Guillaume Gaullier 09 Nov '23

09 Nov '23

Hello, A question for Tristan, since I know you read this list. :-) I have a cryoEM map that was produced with C7 symmetry enforced. I can fit the alphafold prediction of one protomer, and am pretty confident in this initial rigid fit because the map is good. Now with Tom's help I know how to generate the C7 symmetric assembly and store the symmetry info in a cif file with a single protomer, so I can regenerate the heptamer as needed (and this seems like the correct way to deposit the end result). But this model still needs proper refinement: the rigid fit shows that the conformation predicted by alphafold deviates from the map at several locations. What is a sensible refinement strategy for something like this? Because symmetry was enforced for the map, I am inclined to refine only a single protomer and add the correct symmetry info that will regenerate the heptamer. But don't I need the neighboring protomers during refinement, for the interface residues to behave correctly during MDFF? I would think so. Not sure what to do, some advice would be very helpful. Thank you in advance, Guillaume När du har kontakt med oss på Uppsala universitet med e-post så innebär det att vi behandlar dina personuppgifter. För att läsa mer om hur vi gör det kan du läsa här: http://www.uu.se/om-uu/dataskydd-personuppgifter/ E-mailing Uppsala University means that we will process your personal data. For more information on how this is performed, please read here: http://www.uu.se/en/about-uu/data-protection-policy

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How to write biological assembly info in PDB or mmCIF?
by Guillaume Gaullier 08 Nov '23

08 Nov '23

Hello, I have a cryoEM map that was generated with C7 symmetry enforced, with its symmetry axis parallel to the z axis in ChimeraX. I fetched a prediction from AlphaFoldDB and docked it in the map. So far, so good. I can generate the other protomers with a command like this: sym #1 C7 axis z center cofr (assuming #1 is the single protomer from AlphaFoldDB, and the cofr is correctly lying on the symmetry axis, which I get sufficiently close if I center the view on the map) Now, because symmetry was enforced for the map, it makes no sense to model, refine and store the entire heptamer. I should be able to do everything with a single protomer, and store relevant info as "biological assembly" so the heptamer can be regenerated from the protomer. At least if I am understanding this correctly. I tried the above command, or this variant: sym #1 C7 axis z center cofr addMmcifAssembly true And subsequently saving in PDB or mmCIF format, but none of this produces what I want, which is a file containing the single protomer + assembly info. I either get a file with the single protomer or a file with the heptamer, in both cases without any biological assembly info. I looked up the options of the save command for PDB and mmCIF format, but found nothing that seemed relevant to this problem. Is there a way to do this? Or am I misunderstanding something? Related question: it might make sense to use the whole heptamer for refinement, so all interfaces between protomers "see" each other (probably important when using ISOLDE). What is the best way to deal with this? Build and refine the whole heptamer and save only a single protomer + assembly info at the very end? Or have the symmetry enforced from the beginning, throughout the whole refinement process, and really ever refine a single protomer? (7 times less work, so probably the preferred option). Thank you in advance, Guillaume När du har kontakt med oss på Uppsala universitet med e-post så innebär det att vi behandlar dina personuppgifter. För att läsa mer om hur vi gör det kan du läsa här: http://www.uu.se/om-uu/dataskydd-personuppgifter/ E-mailing Uppsala University means that we will process your personal data. For more information on how this is performed, please read here: http://www.uu.se/en/about-uu/data-protection-policy

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Modeller down
by Dominik Dekleva 08 Nov '23

08 Nov '23

Hi My name is Dominik Dekleva, phd student at the University of Ljubljana. I'm attempting to use the Modeller feature in ChimeraX but doesn't seem to be working. Is the webservice down? Best regards, Dominik Dekleva

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Alphafold2_multimer on chimeraX
by Margulies, David (NIH/NIAID) [E] 08 Nov '23

08 Nov '23

Beginning yesterday, I have had repeated failure of alphafold2_multimer running through chimerax to generate models of two protein complexes (Ab H cand L chains, for instance). Individual chains work fine. The error from Colab AI says: The error is due to a bug in the ColabFold library. The kabsch function in the colabfold.py file is using the linalg.svd function to calculate the singular value decomposition of a matrix. However, the linalg.svd function is not guaranteed to converge, and in some cases it can fail to converge. This can cause the kabsch function to fail, and in turn cause the plot_protein_backbone function to fail. The bug has been fixed in the latest version of the ColabFold library, which is available on GitHub. To fix the error, you can upgrade to the latest version of the library. You can do this by running the following command in the Colab notebook: content_copy !pip install colabfold --upgrade Use code with caution<https://g.co/legal/generative-code> Once you have upgraded to the latest version of the library, you can run the code again and the error should be fixed. Can you advise? Thanks for your help. D David H. Margulies, MD, PhD Chief, Molecular Biology Section Laboratory of Immune System Biology National Institute of Allergy and Infectious Diseases National Institutes of Health Bldg. 10; Room 11D12 10 Center Drive Bethesda, MD 20892-1892 Email: dmargulies(a)niaid.nih.gov<mailto:dmargulies@niaid.nih.gov>, dhm(a)nih.gov<mailto:dhm@nih.gov> Ph: 301-496-6429 Fax: 301-480-7352 Web: https://www.niaid.nih.gov/research/david-margulies-md-phd “Public service is a public trust, requiring employees to place loyalty to the Constitution, the laws, and ethical principles above private gain.” – executive order 12674, https://www.federalregister.gov/documents/2016/02/17/2016-03214/standards-o…<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.federalregister.go…> Disclaimer: The information in this e-mail and any of its attachments is confidential and may contain sensitive information. It should not be used by anyone who is not the original intended recipient. If you have received this e-mail in error please inform the sender and delete it from your mailbox or any other storage devices. National Institute of Allergy and Infectious Diseases shall not accept liability for any statements made that are sender’s own and not expressly made on behalf of the NIAID by one of its representatives.

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Zone interaction in rRNA
by tim smith 07 Nov '23

07 Nov '23

How do we select a zone in ribosomal RNA (nucleotide residues of rRNA) to visualize all its interaction interfaces with ribosomal proteins/H2O/ions using ChimeraX? Thank you for your support. Thank you. Best Tim

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Dynamic bonds
by Michael Patzschke 06 Nov '23

06 Nov '23

Dear colleagues, I have a trajectory from an ab initio MD run. The output is in the form of concatenated .xyz information. I can open and visualise this in ChimeraX, but the bond topology is determined from the first step. As the simulation progresses, bonds are stretched and the broken bond in my example just gets drawn, although the distance of the involved atoms gets larger then 7 Å by the end of the simulation. Is there a way to use dynamic bonds in ChimeraX? By this I mean that the bonds are only drawn when the distance of the involved atoms is below a certain threshold. I would appreciate any help in the matter. Kind regards, Michael Patzschke

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Change default colour cycle for EM maps
by James Hooker 06 Nov '23

06 Nov '23

Hello all, I am looking for a way to change the qualitative colour cycle in ChimeraX from the default (grey, yellow, blue, purple, pink, …). I have flicked through the online documentation, but have not yet found a solution. Many people must have desired to do this at some point, right? Any advice is welcome! Best, James

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commandline to hide a map region or set a transparency in chimeraX
by Rayees Mattoo 06 Nov '23

06 Nov '23

Hi, I was wondering if there is a command line in chimeraX to hide a region of the map. To be more specific if I have to hide map around a model #1 chain A, how could I do that? Also, using the same case how do I set a transparency of 50% for the map around the chainA model #1? Actually, I want to make a movie of the vseries where I need to hide/delete/transparent some portion of the map to show the internal details of the map while playing the vseries. Any suggestions are welcome. Best

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