August 2015 - Chimera-users - RBVI Mailing Lists

How to select a plane from the command line
by JUAN PABLO REYES VALVERDE 17 Aug '15

17 Aug '15

Dear UCSF Chimera Team: Please, I would much appreciate your advice on the following: First issue: Given a number of planes - calculated/created through the 'define' command - I would like to select one of them, with some command entered at the command line .... How can I do it? The reason why I want to select it through the command line, and not by directly by clicking at it at the axes/planes/centroids table, is because later I would like to use the command inside a runCommand statement, in a Python/IDLE script (with *.py extension) ... Second issue: By the way, do you think this piece of code could work? Assume that the desired plane is already selected .... I want to internally handle the plane as 'p1' in my Python code: p1= chimera.Plane() from chimera import selection p1= selection or perhaps this single instruction ..... p1= chimera.selection Let me try to explain: Within my Python code, I want to have a way to make reference to a plane created by the 'define' command ( should I call it a ' handle'? ... not sure whether it is the correct term ...). Well, I hope that I managed to make it sufficiently clear ... Thanks in advance for your kind attention. Cheers, Juan Dr. Juan Pablo Reyes Valverde Laboratorio de Neurobiología Molecular y Celular (D15) Instituto de Neurobiología UNAM Campus UNAM Juriquilla Boulevard Juriquilla 3001 Querétaro, QRO CP 76230 MÉXICO Tel +52 (442) 2381064

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Charges for PTR+DT
by Amali Guruge 17 Aug '15

17 Aug '15

Dear all, I have to prepare the pdb structure 1K4T to my study. When I do the dock prep process, it gives net charges as, PTR+DT -2 TGP +0 I added charges for standard resides by AMBER ff12SB. For other residues, I added charges by Gasteiger method. My problem is why PTR+DT gives -2 charge? I am not familiar with this one. <http://www.google.lk/intl/en/options/> Can anyone help me? Thank you.

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Modification of ribbon scaling to intersect guide atoms at termini and chain breaks?
by Oliver Clarke 14 Aug '15

14 Aug '15

Suggestion - would it be possible at some point in the future to add a new ribbon scaling option (I guess in Chimera 2.0 or later) so that all internal residues behave like the current “Bspline” scaling, but residues at termini or chain breaks behave like “cardinal” - where the ribbon path exactly intersects the guide atoms? The attached image illustrates the kind of situation this would address - where one wants to show secondary structure in cartoon, but pick out a loop or structural feature of interest in backbone or CA+sidechains, with no ugly discontinuities between the all-atom and ribbon representations. This would allow seamless mixing of nice looking cartoon representation and nice looking backbone or C-alpha+sidechains representation, which I don’t believe is possible at the moment. Cheers, Oliver. Also, in case anyone finds it useful, the following alias applied to a selection or model will generate the CA+sidechains representation depicted below: #Show CA trace with sidechains #Usage: ca_and_sidechains #model_id (or selection/atom-spec) alias ^ca_and_sidechains sel $1; namesel tmp; ~ribbon tmp; ~disp tmp; sel tmp&@CA&protein; repr stick sel; disp sel; setattr m stickScale 1.00 tmp; sel side chain/base.without CA/C1'&tmp; repr stick sel; disp sel; setattr b radius 0.1 sel; color orange tmp; color byhet tmp; sel @CAA |@CB; namesel tmp2; sel tmp&tmp2; repr stick sel; setattr b radius 0.1 sel; sel @CD,N&:pro&tmp; disp sel; repr stick sel; setattr b radius 0.. 1 sel; ~sel

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~select doesn't work on axes?
by Oliver Clarke 14 Aug '15

14 Aug '15

The command "~sel” does not unselect selected axes/planes/centroids - is this intended, and/or is there another way to unselect these objects from the command line? Also, is there a command to undisplay selected axes/planes/centroids? I can only figure out how to do so from the GUI but I would like to do this from the command line, as when you have many axes defined and only want to hide a few it would be easier to have an equivalent of “~disp sel” rather than hunting for the specific axes in the Axes/Planes/Centroids list. Cheers, Oliver.

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odd chimera benchmark performance
by Dan Lin 13 Aug '15

13 Aug '15

Hello: I was wondering if anyone had any experience tracking down performance problems in chimera. I've noticed that I am getting really sluggish performance when managing a lot of atoms, even when everything is shown as backbone traces only. To take a look at the performance, I ran the benchmark and got the following numbers: Volume benchmark scores surface mesh contour solid recolor 981 1291 280 589 393 Null Wire Stick BStick Ribbon Sphere Ops 6249.5 158.7 1.5 0.9 27.4 0.4 89.3 compared to a benchmark posted on the website of the same graphics card: 2125 2026 302 512 491 213 492 452 3259 169 128 Apparently I'm getting awful benchmarks for most of the molecule benchmarks, while the volume performance is pretty comparable. I re-ran the molecule benchmarks to make sure they were reproducible and got pretty much the same numbers. Would anybody have any suggestions for figuring out what's going on? For reference, I'm running ubuntu 12.04 with up to date nvidia drivers for a GTX 560 Ti. Thanks, Dan

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axis-axis distance definition
by Oliver Clarke 13 Aug '15

13 Aug '15

Quick question - how is the distance between two axes (as reported by Axes/Planes/Centroids) calculated? Is it the minimum distance between two axes (I guess yes, because it does not seem to match the center to center distance)? And does it assume the axes are of infinite length, and calculate the displacement required for them to intersect, or does it measure the minimum distance between the axes with the length and end positions as displayed? Cheers, Oliver.

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place label at arbitrary position in 3D
by Oliver Clarke 13 Aug '15

13 Aug '15

In case it is useful to anyone else - I was trying to figure out a way to place a label at an arbitrary position in 3D, so that I can for example generate a chimera session of a protein with all helices labeled and annotated appropriately. I couldn’t figure out a way to easily do this with the built in tools (rlabel, labelopt etc all seem to require you to set an offset from an atom in the structure), so I made the following alias, which gets around this by placing an invisible marker atom at the center of rotation (which I mostly keep locked to the center of view), and attaching a label to that. Hope it is useful to somebody else too. #Place label here (at center of rotation). #Usage: label_here "label_text" (replace spaces in desired label text with _; they will be replaced by spaces in label) alias ^label_here ~sel; ac mc; color black sel; repr bs sel; vdwdefine 0.01 sel; setattr a label $1 sel; transparency 100,a sel; ~sel Cheers, Oliver.

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curved helices - cylinder representation?
by Oliver Clarke 12 Aug '15

12 Aug '15

Hi all, I’d like to have an extended version of the “Pipes and planks” representation, where helices are represented as cylinders, except as a regular, easily modifiable ribbon representation, and allowing for helix curvature rather than breaking up curved helices. I realize this is not currently implemented and is unlikely to be addressed until Chimera 2.0 due to the many other more important things on the drawing board, so I’m trying to figure out a way to hack something together that will generate acceptable results in the meantime. I figure that one way to do this might be to use a create a pdb file with guide atoms located on the helix axis, which one can approximate by placing a guide atom (P or CA) at the center of mass of a six residue sliding window of C-alpha atoms, and then use these guide atoms to create a thick, smoothed (with B-spline) licorice tube. This works quite well for an individual helix, as you can see in the attached pics, but I am a little at a loss as to how to automate this procedure across all the helices in a structure, or even for a given (selected) helix (and it’s only really the helices I care about - strands are fine as is, but having a curved cylinder representation for helices would be very handy). I guess I can do so using a python script of some sort, but if anyone has any pointers as to how to get started, they would be most appreciated. So I guess I need to loop through all the residues in a selection, calculating the center of mass in a sliding window and placing atoms as appropriate, then write out a pdb file with appropriate atom names. This shouldn’t be too hard, but if anyone can point me towards code that I can adapt for this purpose it would be most helpful. Cheers, Oliver.

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question
by A G Szabo 11 Aug '15

11 Aug '15

Today I was trying to Fetch a series of files from the PDB. Their accession codes are 3J7O, 3J7Q, 3J7R, and 3J7P. These are structures of the ribosome complexed with a trimeric translocon, Sec61. Each time Chimera responded with an error message indicating that there was no such file. The files come from a paper by R M Voorhees, (2014) Cell 157:1632. I went to the PDB website and was able to access each of the files. So they do exist. However, when I tried to visualize them using Protein Workshop the structure that appeared was a mixture of surfaces and ribbon structures. I was not able to do anything with any of the structures using Protein Workshop. I could not delete any of the several components, nor change them to ribbon structures. I have been able to fetch, using Chimera, other PDB files that have the entire ribosome complexed with proteins of interest. I sent a message to PDB relating what I have encountered and am waiting for a response. My question to Chimera is to determine if there is a work around to get at any of these files. Thank you Arthur G. Szabo Professor Emeritus Chemistry Wilfrid Laurier University

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is Chimera able to do spin albeling in silico
by Shu-Hao Liou 10 Aug '15

10 Aug '15

Hi, Thank you for reading this email. I'd like to have a rough protein structure with certain spin label on one of the cysteine. Is chimera be able to provide the reasonable structure for that? Sincerely, Shu-hao Liou UC Davis

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