June 2014 - Chimera-users - RBVI Mailing Lists

Constrainted fitting
by Christoph Wigge 22 Mar '19

22 Mar '19

Dear all, I would like to fit two protein monomers that form a dimer into an em density map. I know from previous mutagenesis studies that the binding takes place with two tryptophan residues and the counterpart binding pocket. How can I set this interaction as fixed so that chimera fits the rest of the molecule according to the density map without continuously changing this part of the essential protein protein interaction? I would like to fit that interaction manually and then exclude it from the automatic procedure. Thank you very much in advance. Bests Christoph Wigge

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volume planes tool
by Jeff Triffo 22 Jun '16

22 Jun '16

hi folks, anyone know if the volume plane tool will support arbitrary orientation of the plane any time soon? -Jeff

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suggested improvements
by Dougherty, Matthew T 02 Jul '14

02 Jul '14

1) first suggestion on the sym command the following is defined icosahedral symmetry I[,orientation] around center Example: i,n25 where orientation can be: 222 (default) - with two-fold symmetry axes along the X, Y, and Z axes 2n5 - with two-fold symmetry along X and 5-fold along Z n25 - with two-fold symmetry along Y and 5-fold along Z 2n3 - with two-fold symmetry along X and 3-fold along Z 222r - same as 222 except rotated 90° about Z 2n5r - same as 2n5 except rotated 180° about Y n25r - same as n25 except rotated 180° about X 2n3r - same as 2n3 except rotated 180° about Y In the chimera tool->higher order structure -> the icosahedral structure it defines similar orientations, assume in the same order. It would be helpful on the selections to include the sym syntax as part of the icosahedral structure text ie {222} xyz 2 fold {2n5} x 2 fold z 5 fold 2) second suggestion When reading an MRC file I occasionally see situations that make me question whether the file is EMDB complaint. It would be good to have the means to dump the MRC header, even if chimera refuses to read the file in its entirety. Matthew Dougherty National Center for Macromolecular Imaging Baylor College of Medicine ===========================================================================

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Re: [Chimera-users] Attaching a Probe to Modify an Existing Amino Acid
by Eric Pettersen 02 Jul '14

02 Jul '14

Hi Shana, Well, you might be able to get away with just setting that atom's "name" attribute to "SD", but since you are writing Python code anyway and residues hold their atoms in a name-indexed structure, it would be better to do it the right way by removing the atom from the residue, renaming it, and putting it back. Assuming you have the CYS residue in a variable named 'cys': s = cys.findAtom("SG") cys.removeAtom(s) s.name = "SD" cys.addAtom(s) --Eric On Jun 19, 2014, at 11:25 AM, Shana Burstein <sburstei(a)haverford.edu> wrote: > Hi Eric, > I was able to move the CN atoms from the CN residue to the CYS residue and call it MSCN. I actually need it to be called MSCN in order for the modified residue to be recognized by a force field in an MD simulation. My only problem now is that the S atom of cysteine is labeled as "SG" and I need it to be called "SD." I know how to do this by going through the Tool menu, but is there a way to automate that? > > Thanks, > Shana > > > On Wed, Jun 18, 2014 at 2:35 PM, Eric Pettersen <pett(a)cgl.ucsf.edu> wrote: > Hi Shana, > If you were starting from scratch, the procedure to add the CN would probably be simpler by using chimera.molEdit.addDihedralAtom() to add the C and then the N at the appropriate bond length, angle and dihedral and then rename the residue with: r.type = "MSCN". Nonetheless, you have come a long way down the road with your script and probably would not prefer to start over from scratch! So let's suppose you have your two relevant Residue instances in variables named 'cys' and 'cn'. The code to do what you want would be: > > for a in cn.atoms: > cn.removeAtom(a) > cys.addAtom(a) > cys.type = "MSCN" > # empty residues are problematic in various parts of Chimera, so... > cn.molecule.deleteResidue(cn) > > If you don't know how to get the 'cys' and 'cn' variables but you know an atom specifier that selects each, you can use this code to set the variables: > > runCommand("sel atom-spec-for-cys") > cys = chimera.selection.currentResidues()[0] > runCommand("sel atom-spec-for-cn") > cn = chimera.selection.currentResidues()[0] > > There's a couple of further relevant things here. Strictly speaking, 4-letter residue names are not legal in PDB format (while there is a column where a 4th character could go, according to the format definition that column is supposed to be blank). Therefore if you export your modified structure to other software programs, they may or may not be able to handle the 4-character residue name without problems. Therefore I recommend you use the same residue name that the PDB uses for this moiety, 4CY (which can be found in the 3or0 entry). > Along the same lines, 4CY can actually be found in the SwissSidechain rotamer library plugin for Chimera (SwissSidechain - A database of non-natural side chains) and therefore if you install that plugin then the entire substitution process becomes a single command: swapnaa 4CY cysteine-atom-spec. > > --Eric > > Eric Pettersen > UCSF Computer Graphics Lab > http://www.cgl.ucsf.edu > > On Jun 18, 2014, at 6:50 AM, Shana Burstein <sburstei(a)haverford.edu> wrote: > >> Hello, >> I am an undergraduate student at Haverford College and I am attempting to attach thiocyanate probes onto different sites along a protein by first replacing the existing amino acid with a cysteine and then by adding a C and N onto the S- of the Cys residue. I know it is possible to carry this out manually using Tools>Structure Editing>Modify Structure, but I am hoping to automate this process by calling an external .py script that will primarily contain a list of preexisting Chimera commands. >> >> I have been successful at converting the targeted amino acid to Cys using "swapaa," building a CN residue called MSCN (using the createMolecule.py as a guide), combining the two models into one ("combine selected close True") and forming a bond between the Cys S and CN C atoms ("bond"). >> >> At this point, I am seeking help in automating the renaming of the modified residue to MSCN. Currently, Chimera sees this residue as two different separate residues called CYS and MSCN. Is there a way to combine these two structures so that the label corresponds to MSCN and the residue number corresponds to CYS? >> >> Sincerely, >> >> Shana Burstein >> Haverford College '15 >> _______________________________________________ >> Chimera-users mailing list >> Chimera-users(a)cgl.ucsf.edu >> http://plato.cgl.ucsf.edu/mailman/listinfo/chimera-users > > > >

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Re: [Chimera-users] Fo-Fc electron density maps
by Oliver Clarke 30 Jun '14

30 Jun '14

Actually adding a second arg works well, thanks! So now I have: alias normalize_to_rms vop scale $1 rms 1 modelID $2; close $1; volume $2 capfaces false style mesh meshlighting false squaremesh false color blue; sop cap off alias split_diff_map vop scale $1 rms 1 modelID $2; close $1; volume $2 capfaces false style mesh meshlighting false squaremesh false level -3 color red level 3 color green; sop cap off Where the first one just normalizes to rms and colors blue, and the second one also normalizes but creates two appropriately colored contours, and I can call these as e.g. split_diff_map #0 #1, where #0 is the input map number and #1 is the desired output map number. Cheers, Oliver. On Jun 30, 2014, at 5:06 PM, Tom Goddard <goddard(a)sonic.net> wrote: > Making a macro create map #1000 does not work well, since the second time you use it it will try to make another model #1000. You could add a second argument to your macro that specifies the output model number. Or you make your macro that sets all the volume settings (mesh, capfaces, …) take a model number. None of the choices is very good. > > Tom > > On Jun 30, 2014, at 2:01 PM, Oliver Clarke <olibclarke(a)gmail.com> wrote: > >> Ah right - that’s okay then, I can just assign it to modelID 1000 then, on the assumption that I’ll never have 1000 models open at the same time. >> >> Thanks! >> >> Oliver. >> On Jun 30, 2014, at 4:59 PM, Tom Goddard <goddard(a)sonic.net> wrote: >> >>> There is no special variable to indicate the last created map for use in Chimera commands. In a vop command you can include an option “modelId #5” to assign the id number of the new model. So your macro could take the model id you want for the new map. If you use the vop (volume operation) command to create a new map and don’t specify the modelId option then the new map has the lowest unused model number. There are no output values assigned to variables in the Chimera command language, so it is quite limited. >>> >>> Tom >>> >>> >>> On Jun 30, 2014, at 11:32 AM, Oliver Clarke wrote: >>> >>>> Thanks Tom and Elaine, that’s very helpful! >>>> >>>> While we’re on the topic of macros/aliases, is there any way to refer to the model ID of an output map of a command as a variable in an alias? >>>> >>>> For example, in the normalize_to_rms macro below, I would prefer to apply all the volume settings to just the map I am normalizing, rather than all open maps, but I can’t predict the model ID of the output map because it depends on how many maps I have open. >>>> >>>> This would be handy for stringing together multiple map/model manipulations in a single macro - e.g. to normalize a map to rms, generate two contours and color them appropriately, without disturbing any other open maps. >>>> >>>> Cheers, >>>> Oliver. >>>> >>>> On Jun 30, 2014, at 2:00 PM, Tom Goddard wrote: >>>> >>>>> Hi Oliver, >>>>> >>>>> To simplify your Chimera macros a bit you can put multiple options in one volume command. Instead of >>>>> >>>>> volume # capfaces false; volume # style mesh; volume # meshlighting false; volume # squaremesh false >>>>> >>>>> you can change settings for all open maps with >>>>> >>>>> volume # capfaces false style mesh meshlighting false squaremesh false >>>>> >>>>> Tom >>>>> >>>>> >>>>> On Jun 28, 2014, at 3:14 PM, Oliver Clarke wrote: >>>>> >>>>>> Dear Egor, >>>>>> >>>>>> In addition to Elaine’s suggestion of unchecking “Cap high values at box faces", I use the following aliases to make difference maps more familiar in style to a crystallographer: >>>>>> >>>>>> First, to just normalize the map to RMS (as per coot etc) and adjust to get a mesh, turn capping, mesh lighting off etc: >>>>>> >>>>>> alias normalize_to_rms vop scale $1 rms 1; close $1; volume # capfaces false; sop cap off; volume # style mesh; volume # meshlighting false; volume # square mesh false >>>>>> >>>>>> Second, to split the map into two maps (one positive, one negative), which can then be colored green and red respectively: >>>>>> >>>>>> alias split_diff_map vop threshold $1 minimum 0; vop threshold $1 maximum 0; close $1; sop cap off; volume # style mesh; volume # meshlighting false; volume # squaremesh false; >>>>>> >>>>>> I add these two lines in a “chimera_aliases.com” file, which you can tell Chimera to read at startup under Favorites—>Preferences—>Command Line. >>>>>> >>>>>> You can then run these commands from the chimera command line, e.g. normalize_to_rms #1 or split_diff_map #1 if your map number is 1. Then just adjust the contours and colors in the volume viewer and you are good to go. >>>>>> >>>>>> I don’t know how to automatically color the resultant maps, because there does not seem an obvious way to predict their model numbers, but I am sure there is a way to do that too, perhaps via some python trickery. >>>>>> >>>>>> This is all kind of a work around of course - there may be a way to color a map by density value (such that all positive regions are green, and all negate regions are red), but I couldn’t figure out how to do it. >>>>>> >>>>>> Best, >>>>>> Oliver. >>>>>> _______________________________________________ >>>>>> Chimera-users mailing list >>>>>> Chimera-users(a)cgl.ucsf.edu >>>>>> http://plato.cgl.ucsf.edu/mailman/listinfo/chimera-users >>>>>> >>>>> >>>> >>>> >>> >> >> >

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Re: [Chimera-users] Fo-Fc electron density maps
by Oliver Clarke 30 Jun '14

30 Jun '14

Dear Egor, In addition to Elaine’s suggestion of unchecking “Cap high values at box faces", I use the following aliases to make difference maps more familiar in style to a crystallographer: First, to just normalize the map to RMS (as per coot etc) and adjust to get a mesh, turn capping, mesh lighting off etc: alias normalize_to_rms vop scale $1 rms 1; close $1; volume # capfaces false; sop cap off; volume # style mesh; volume # meshlighting false; volume # square mesh false Second, to split the map into two maps (one positive, one negative), which can then be colored green and red respectively: alias split_diff_map vop threshold $1 minimum 0; vop threshold $1 maximum 0; close $1; sop cap off; volume # style mesh; volume # meshlighting false; volume # squaremesh false; I add these two lines in a “chimera_aliases.com” file, which you can tell Chimera to read at startup under Favorites—>Preferences—>Command Line. You can then run these commands from the chimera command line, e.g. normalize_to_rms #1 or split_diff_map #1 if your map number is 1. Then just adjust the contours and colors in the volume viewer and you are good to go. I don’t know how to automatically color the resultant maps, because there does not seem an obvious way to predict their model numbers, but I am sure there is a way to do that too, perhaps via some python trickery. This is all kind of a work around of course - there may be a way to color a map by density value (such that all positive regions are green, and all negate regions are red), but I couldn’t figure out how to do it. Best, Oliver.

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Calculating ASA for side chain
by saadraza＠bs.qau.edu.pk 29 Jun '14

29 Jun '14

Respected Admin I would like to know if there is any way to modify the calculation of Accessible Surface Area (ASA) to calculate only the ASA for the side chain or a particular group of atoms in chimera. If not possible could someone guide me to some other tool. I will be obliged if someone sort this problem for me Regards Saad Raza

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Fo-Fc electron density maps
by Egor Tchesnokov 28 Jun '14

28 Jun '14

Hello, Is there a way to display Fo-Fc electron density maps so that "red/negative" and "green/positive" densities are displayed at the same time. Thank you Egor

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Urgent: surface calculus
by Olivier Sire 27 Jun '14

27 Jun '14

Hello, I am in a hurry to generate a surface object with 2FJG complex to be exported in a STL format for 3D printing. This item will be presented for a local event organized by the Ligue contre le Cancer. I have download Chimera as absolute beginner and I am facing a need for splitting the (too big ?, multi-chain) complex. The function Action / Surface / show generates the splitting solution. Could you help me and guide me ? Thanks in advance Regards Olivier Sire -- *Olivier SIRE * / Professeur à l'Université de Bretagne-Sud / ------------------------------------------------------------------------ Laboratoire d'Ingénierie des Matériaux de Bretagne Campus de Tohannic BP575 56017 VANNES cedex Tél. 02 97 01 71 48 Fax. 02 97 01 70 70 Mob. 06 89 48 25 24 olivier.sire(a)univ-ubs.fr UNIVERSITÉ DE BRETAGNE-SUD http://www-limatb.univ-ubs.fr/ <http://www.univ-ubs.fr/>

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Build a quadruplex
by sette＠uniroma2.it 26 Jun '14

26 Jun '14

Dear all, Im interested to create a rough model of a quadruplex molecule using a specific sequence. One possibility could be to load a pdb structure of a quadruplex and « mutate » each nucleotide with the correct one. Is this feasible with Chimera ? Alternative suggestions are appreciated as well. Thanks for your help, Marco Dr.Marco Sette, Ph.D. Department of Chemical Sciences and Technology University of Rome, "Tor Vergata" via della Ricerca Scientifica, 00133, Rome, Italy e-mail: sette(a)uniroma2.it e-mail: m77it(a)yahoo.it Tel.: +39-0672594424 Fax: +39-0672594328 www.rete29aprile.it ---------------------------------------------------------------- Invito da parte dell'Ateneo: Il tuo futuro e quello della Ricerca Scientifica hanno bisogno del tuo aiuto. Dona il 5 x mille all'Universita' di Roma Tor Vergata codice fiscale: 80213750583 http://5x1000.uniroma2.it

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Chimera-users June 2014