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Questions and answers => RNA structures (DSSR) => Topic started by: kanavkalra on May 20, 2018, 09:36:50 am

Title: Water H-Bonding with surrounding residues
Post by: kanavkalra on May 20, 2018, 09:36:50 am: Dear Dr. Xiang-Jun Lu,
May I know if there exists any option that could help me get data for the Water H-Bonding with the surrounding residues?

Regards,
Kanav Kalra
Title: Re: Water H-Bonding with surrounding residues
Post by: xiangjun on May 20, 2018, 10:26:30 am: Hi,

Thanks for posting on the 3DNA Forum!

Could you elaborate on what you want to achieve specifically? Please use a concrete example so that I (and others) can better understand you.

Best regards,

Xiang-Jun
Title: Re: Water H-Bonding with surrounding residues
Post by: kanavkalra on May 20, 2018, 05:23:54 pm: Hi,
Below is an example:

In PDB id: 2GDI,

For instance, if we want to find out possible H-bonds between a water molecule 'HOH-373' from chain X with the surrounding atoms from the environment. The output could be as follows:

1) O2P atom of G76 chain X; with the distance between O atom of HOH-373 and O2P atom of G76 of 2.79 Angstrom.
2) HOH 492X; with the distance between O atom of HOH 373 and O atom of HOH492X of 2.58 Angstrom.
3) N7 of G76 X; with the distance between O of HOH 373 and N7 atom of G76X of 2.84 Angstrom.

So the above three atoms are within the H-bonding distances if we consider the distance criterion of less than 3.5 Angstrom between the donor and acceptor atoms.
Title: Re: Water H-Bonding with surrounding residues
Post by: xiangjun on May 20, 2018, 06:21:41 pm: Try running DSSR with the --h2o (or --water) option. For example,

Code: [Select]
x3dna-dssr -i=2gdi.pdb --h2o --get-hbond | grep X.HOH373 1415 3572 #400 o 2.790 O:O OP2@X.G76 O@X.HOH373 1427 3572 #407 o 2.836 N:O N7@X.G76 O@X.HOH373
By design, DSSR does not output H-bond between waters. So your item 2), i.e. the H-bond between X.HOH373 and X.HOH492, is not available. It should be straightforward to add X.HOH494 to the list, based on available info and a distance cutoff. You're welcome to contribute back your code/script with examples so the community could benefit from it.

HTH,

Xiang-Jun