[Chimera-users] showing backbone for some residues and not others

A G Szabo agszabo at bell.net
Mon Dec 5 13:54:02 PST 2016


Elaine

Your message was helpful as it taught me how to specify residues within one
chain out of a large number of chains, i.e.  Chain #0.1: Res#.K  That is
Chain #0.1.K and res#.

However, after trying a number of command ideas, I do not think it is
possible to do what I would like to do.


I know how to hide all the chains in the data base, and visualize the
individual the ribbons of the chains that I want. I visualize the ribbons
for Chain #0.1 E, and #0.1 K. PDB 2LMN

 I then go to "Tools" ;  "Sequence" and select two chain sequences. I select
a residue, Met 35 on #0.1 E, and then, "Actions" ; "Atoms/bonds" ; "Show".
The side chain Met 35  pops up on Chain #0.1 E.   then "ball and stick" (no
problem so far have  done this many times) the side chain of Met 35 shows as
balls and sticks. If I  color the atoms of Met35 a color different from the
ribbon, the CA atom is nicely embedded in the ribbon.

I also know that when I use the command line and enter "disp #0.1:35.E" I
can achieve the same result without having to highlight the residue in the
sequence of that chain. I can visualize several residues using the same
command style.

If I use the command line and enter "ribbackbone", the backbone atoms of Met
35 are displayed.

When one visualizes four or five side chains on a chain, the presence of the
backbone atoms starts to clutter up the image. The backbone atoms do not add
to the information regarding the inter  or intramolecular interactions that
one would like to display between the different side chains.

I then use your suggestion and enter the command "~disp #0.1:35.E @N,C,O,H"

The backbone atoms of Met 35 disappear, BUT the rest of the side chain
remains sitting above the ribbon. There is a gap between the side chain  and
the ribbon.

Further to this imaging, I would like select and visualize some Gly residues
on part of Chain #0.1K. Met35 of Chain #0.1E interacts with these Gly
residues. With "ribbackbone" in effect the Gly residues show up as the five
backbone atoms, C, N, O, and 2 H atoms.

That would be fine but the esthetically it doesn't look good with the Met35
side chain and others just hanging there not attached to ribbon, and if  I
turn "ribbackbone" off in order to get CA of Met35 in the ribbon, then the
Gly residues no longer have any atoms visualized and disappear into the
ribbon..

I  have tried various permutations, such as "disp #0.1:33.K,37.K,38.K
@N,C,O,H" hoping that I might be able to visualize the Gly residues, it
doesn't work.

So that leads me back  to my original statement that I don't think I can
achieve the image that I would like to present.

A suggestion would be if one could apply "ribbackbone" only to a specific
chain in the model instead of to the entire model.

Thanks your assistance, I am learning more and more about nuances of
Chimera, which I recommend as a very user friendly package especially if you
use the menu section. One thing I have had trouble understanding is the
"Inspect Selection" menu that is available under "Actions". You have
suggested that I use that on a couple of occasions, but it  is a bit
unfathomable. Tried to check it out in the Help sections but was unable to
make any progress in understanding it.

Best regards

arthur


-----Original Message-----
From: Elaine Meng [mailto:meng at cgl.ucsf.edu] 
Sent: December-02-16 3:38 PM
To: A G Szabo
Cc: chimera-users at cgl.ucsf.edu
Subject: showing backbone for some residues and not others

Hi Arthur,
I believe I understand completely, but I can only repeat my suggestions from
before.  You would use "ribbackbone" to allow both ribbon and backbone
atoms, and then use "disp" to show the atoms you want to see and "~disp" to
hide the atoms you don't want to see.  Don't know what you mean by "didn't
work".

The exact disp and ~disp commands depend on the models, chains, residues,..
in your structure.

Here is an example with PDB entry 2gbp, pretending I want to see all atoms
of residues 40-50 but sidechain only of residues 20-30;  everything in that
structure is chain A:

open 2gbp
ribbackbone
~disp
disp #0:40-50.A
disp #0:20-30.A & with CA/C1'

The last part of the last line means sidechains only.  However, another way
to the same result is to display all atoms of those residues but then hide
their backbone atoms like we talked about before:

disp #0:20-30.A
~disp #0:20-30.A at n,c,o,h

Still one more step if you don't want fake CA-CA bonds between adjacent
residues for which you are showing sidechain only:

setattr m autochain false

Elaine
-----
Elaine C. Meng, Ph.D.                       
UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of
Pharmaceutical Chemistry University of California, San Francisco



On Dec 2, 2016, at 11:21 AM, A G Szabo <agszabo at bell.net> wrote:

> Elaine
> 
> The essential issue is that all of the Atoms of Gly are part of the 
> backbone. So in order to visualize those atoms one has to turn them on 
> with ribbackbone. But visualizing the backbone atoms of other residues 
> with longer side chains clutters up the image, and I would rather have 
> the backbone atoms of such amino acids turned off.
> 
> I sent you a power point attachment with the structure I am working with.
> This is the partial structure of a beta sheet amyloid made up of the 
> same peptide all in a stack. So in order to show the key 
> intramolecular interactions in one of the peptides in the stack one 
> can show the selected residues. Only issue is that one cannot 
> visualize Gly in any meaningful way unless ribbackbone is turned on.
> 
> Thanks for your assistance
> 
> Much appreciated
> 
> arthur
> 
> -----Original Message-----
> From: Elaine Meng [mailto:meng at cgl.ucsf.edu]
> Sent: December-02-16 12:47 PM
> To: A G Szabo
> Cc: chimera-users at cgl.ucsf.edu
> Subject: Re: [Chimera-users] question
> 
> Hi Arthur,
> Unfortunately "ribbackbone" only applies to the whole model.  However, 
> it is merely an "enabler" allowing backbone atoms and ribbon to be 
> shown at the same time, if the atoms and ribbon both happen to be 
> displayed for the same residue.  You can still hide (~display) any 
> atoms you don't want to see and hide ribbon (~ribbon) of any residue 
> whose ribbon segment you don't want to see.
> 
> So you would have to use "ribbackbone #0.1" or something like that on 
> the whole model, but then hide all the atoms you don't want, say 
> "~disp #0.1" to hide all atoms, and then to show all atoms of glycines 
> 33,37,38 it could be something like "disp #0.1:33.A,37.A,38.A" (for 
> example, if they are in chain A of model #0.1).
> 
> Again, you can use Selection Inspector instead of commands for many 
> things, although commands are better for doing things with specific
residue numbers.
> I hope this helps,
> Elaine
> -----
> Elaine C. Meng, Ph.D.                       
> UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department 
> of Pharmaceutical Chemistry University of California, San Francisco
> 
> 
> On Dec 2, 2016, at 9:33 AM, A G Szabo <agszabo at bell.net> wrote:
> 
>> You have been very helpful in explaining different  items that use 
>> the
> command line.
>> 
>> I have a PDB file that was determined by NMR. Thus there are a large
> number of chains number as pdb (#0.1) Chain A   etc.
>> 
>> So I know that I can select a single chain, and build up an image 
>> with
> Chains A, B, etc using the #0.1 chain number.
>> 
>> I want to visualize three Gly residues in one chain. So I learned 
>> that I
> can use the command ribbackbone  to visualize the backbone atoms of 
> the amino acids that I  want to show. So when I use that command all 
> the backbone atoms of the residues selected are visualized including 
> the side chains. I also know that if I use the command ~ribbackbone  
> all the backbone atoms are suppressed leaving only the atoms of the 
> side chains. I  know that without any residues or atoms specified the 
> command applies to the whole model.
>> 
>> Now as I said that I  want to visualize three Gly residues in one of 
>> the
> chains. The Gly residue numbers are 33, 37, 38.  They are on Chain #0.1 K.
>> 
>> The information on the ribbackbone  in the  Chimera users guide, 
>> indicates that I should be able  to do this by using parameters 
>> termed atom-spec.  i.e. ribbackbone  atom-spec
>> 
>> 
>> I looked elsewhere for how to designate the parameters for atom-spec 
>> and
> tried a few things, but I was not able to achieve the specificity of 
> showing the backbone atoms of only the Gly residues. I don't think 
> that I have to indicate that I want only the Gly residues in Chain K 
> #0.1 because I can select the Gly residues from the sequence of Chain K
#0.1.
>> 
>> So after this long description of what I want to do, would you kindly
> inform me of how I can visualize the backbone atoms of only Gly.
>> 
>> Thank  you
>> 
>> Arthur G. Szabo
> 
> 
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