Re: [phenixbb] distorted (collapsed) zinc-finger motifs

Hi Hasan, Did you look at the .geo file already to check if the bond and angle restraints are correct for the atoms involved? The .geo file can be very large if you have a large model. An option to reduce the noise for troubleshooting is to cut down the pdb file to just the residues involved and then run phenix.refine --dry-run with the small pdb file. If you get stuck, we could help more if you send us the small pdb file. Ralf ----- Original Message ----

From: Hasan Demirci To: [email protected] Sent: Mon, December 6, 2010 5:47:28 PM Subject: [phenixbb] distorted (collapsed) zinc-finger motifs

Hi,

I am in the middle of refining a 3.5 A (low resolution) ribonucleo-protein complex structure. Two of the proteins in this complex contain "zinc-finger" motif. These zinc-finger motifs instead of forming a cysteine-zinc interactions, cysteines are forming di or in these case tetra-sulfide bridges. Initially, zinc is centered but after refinement 4 cysteines come out collapsed and forming covalent bonds to each other and also distorted and zinc is not at the center anymore.

Below is the phenix.refine zn_link.param file I am using.

Many thanks for advice, Hasan Demirci ----------------------------------------------------------------------------

refinement.pdb_interpretation { disulfide_distance_cutoff = 0.1 } refinement.pdb_interpretation.apply_cif_link { data_link = ZN-CYS residue_selection_1 = chain D and resname ZN and resid 306 residue_selection_2 = chain D and resname CYS and resid 9 } refinement.pdb_interpretation.apply_cif_link { data_link = ZN-CYS residue_selection_1 = chain D and resname ZN and resid 306 residue_selection_2 = chain D and resname CYS and resid 12 } refinement.pdb_interpretation.apply_cif_link { data_link = ZN-CYS residue_selection_1 = chain D and resname ZN and resid 306 residue_selection_2 = chain D and resname CYS and resid 26 } refinement.pdb_interpretation.apply_cif_link { data_link = ZN-CYS residue_selection_1 = chain D and resname ZN and resid 306 residue_selection_2 = chain D and resname CYS and resid 31 } refinement.pdb_interpretation.apply_cif_link { data_link = ZN-CYS residue_selection_1 = chain N and resname ZN and resid 307 residue_selection_2 = chain N and resname CYS and resid 24 } refinement.pdb_interpretation.apply_cif_link { data_link = ZN-CYS residue_selection_1 = chain N and resname ZN and resid 307 residue_selection_2 = chain N and resname CYS and resid 27 } refinement.pdb_interpretation.apply_cif_link { data_link = ZN-CYS residue_selection_1 = chain N and resname ZN and resid 307 residue_selection_2 = chain N and resname CYS and resid 40 } refinement.pdb_interpretation.apply_cif_link { data_link = ZN-CYS residue_selection_1 = chain N and resname ZN and resid 307 residue_selection_2 = chain N and resname CYS and resid 43 } # data_link_ZN-CYS # loop_ _chem_link_bond.link_id _chem_link_bond.atom_1_comp_id _chem_link_bond.atom_id_1 _chem_link_bond.atom_2_comp_id _chem_link_bond.atom_id_2 _chem_link_bond.type _chem_link_bond.value_dist _chem_link_bond.value_dist_esd ZN-CYS 1 ZN 2 SG single 2.340 0.020 loop_ _chem_link_angle.link_id _chem_link_angle.atom_1_comp_id _chem_link_angle.atom_id_1 _chem_link_angle.atom_2_comp_id _chem_link_angle.atom_id_2 _chem_link_angle.atom_3_comp_id _chem_link_angle.atom_id_3 _chem_link_angle.value_angle _chem_link_angle.value_angle_esd ZN-CYS 1 ZN 2 SG 2 CB 109.000 3.000

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-- Hasan DeMirci, Ph.D. Postdoctoral Fellow Department of Molecular Biology, Cellular Biology & Biochemistry Brown University 185 Meeting Street Providence, RI 02912

(401) 863-3652 lab (SFH) (401) 863-6124 lab (ship st) (401) 226-7852 cell

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