- phenixbb - phenix-online.org

Challenging Refinement at 5 A Resolution
by Erik Walinda 28 Feb '14

28 Feb '14

Dear community, This is my first adventure in crystallography and it seems a rather challenging one. I obtained at dataset at 5.06 A resolution of a 600 residue protein. 3 domains of the protein are already solved by earlier x-ray crystallographic studies. While trying to grow better diffracting crystals and waiting for the next chance to shoot crystals at the synchrotron, I am trying to fit the already solved domains into the electron density of the low data set. Although I tried phaser using the solved structures, I never got a TFZ higher than ~ 6.4. Interestingly, Balbes constructed a model which does not contain any of the already solved domains, but, when using the Balbes output in Phaser, I obtain a TFZ score of 11 and an LLG of 330. (4 molecules / ASU; P2221) If this solution is correct, then in principle it should be possible to fit the already known domains into the structure (I am dreaming of something like a electron-microscopy-type fitting or the early ribosome structures). Phenix refinement however raises the Rfree, instead of lowering it. From my limited knowledge in the field I figured this may be that a) this kind of refinement doesnt work at this resolution or 2) the MR-solution was not really a solution. So I was very excited, when I found the recent papers about DEN refinement and Phenix-Rosetta. I am trying DEN refinement first, using the already solved structures as a reference. The den_refine program nicely creates 2760 DEN restraints. However, after 1 cycle (about 6 h of CPU time at 30 processors), the Rfree goes up (Initial: 0.49; final: 0.57). Indeed, the grid search seems not to be successful, since in the grid search for gamma/w, all Rfree values are rather similar and the lowest Rfree is 0.54. So I would like to ask the community, if ... 1) I shouldn't trust the phaser TFZ score too much and maybe it is just no solution after all? 2) the DEN parameters of phenix.den_refine can be optimized to allow to refine a super-low resolution structure? (I am using the standard parameters from the example: https://www.phenix-online.org/documentation/den_refine.htm) 3) 1 cycle is simply not enough and I should let the computation run for a few days to see, if the Rfree drops down later in the run? 4) Even though Phaser gave me the solution in P2221, may it be that I am trying to refine it in the wrong spacegroup and that's why I fail? Sincerely, Erik

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Re: [phenixbb] unusually high B-factors for selected -heavier- atoms
by Kay Diederichs 28 Feb '14

28 Feb '14

Jan, could it be radiation damage? - that would affect the heavier atoms first/most ... To prove/disprove, use zero-dose extrapolation and re-refine. Kay Am 27.02.14 20:13, schrieb phenixbb-request(a)phenix-online.org: > Date: Thu, 27 Feb 2014 09:50:31 -0800 > From: Jan <jan.abendroth(a)gmail.com> > To: PHENIX user mailing list <phenixbb(a)phenix-online.org> > Subject: [phenixbb] unusually high B-factors for selected -heavier- > atoms > Message-ID: <D87628CC-A657-4B4C-B14F-C230C0C2EF00(a)gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi all, > I am refining a pretty high resolution structure (1.65?, P1) with two tetramers of the protein in the ASU using Phenix dev 1630. > Refinement statistics looks really good, R=0.16 Rf=0.18, maps are very clear. However, several sulphur atoms of the protein, and in particular the phosphorous atoms of its cofactor NAD have inflated B-factors, along with distinct FoFc peaks. For instance B-factors for a Met with very well defined density: CB=19.7, CG=27.5, SD=62.2, CE=38.4 > > For some of the residues it is comparable when I refine with or without TLS groups. I used one group per chain of this compact protein, the cofactor is part of each TLS group. Restraints for NAD were generated via eLBOW. When I refine the structure in refmac, using either the standard cif file or the eLBOW generated one, B-factors remain low. > > Any ideas? I am happy to share the data. It is a SSGCID target and will be in the PDB shortly anyway. > > Thanks, > Jan > > > > -- > Jan Abendroth > Emerald BioStructures > Seattle / Bainbridge Island WA, USA > home: Jan.Abendroth_at_gmail.com > work: JAbendroth_at_embios.com > http://www.emeraldbiostructures.com >

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unusually high B-factors for selected -heavier- atoms
by Jan 28 Feb '14

28 Feb '14

Hi all, I am refining a pretty high resolution structure (1.65Å, P1) with two tetramers of the protein in the ASU using Phenix dev 1630. Refinement statistics looks really good, R=0.16 Rf=0.18, maps are very clear. However, several sulphur atoms of the protein, and in particular the phosphorous atoms of its cofactor NAD have inflated B-factors, along with distinct FoFc peaks. For instance B-factors for a Met with very well defined density: CB=19.7, CG=27.5, SD=62.2, CE=38.4 For some of the residues it is comparable when I refine with or without TLS groups. I used one group per chain of this compact protein, the cofactor is part of each TLS group. Restraints for NAD were generated via eLBOW. When I refine the structure in refmac, using either the standard cif file or the eLBOW generated one, B-factors remain low. Any ideas? I am happy to share the data. It is a SSGCID target and will be in the PDB shortly anyway. Thanks, Jan -- Jan Abendroth Emerald BioStructures Seattle / Bainbridge Island WA, USA home: Jan.Abendroth_at_gmail.com work: JAbendroth_at_embios.com http://www.emeraldbiostructures.com

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FAQ high res refinement
by Eike Schulz 28 Feb '14

28 Feb '14

> > Dear all, > > I am currently refining a rather well resolved protein at 0.97Å. However, even > after many cycles of refinement the R-factors are stuck at around Rwork/Rfree > 14.5/16.5. Considering number of aa, Rmerge (3.5%) and resolution this seems > to be too high. I assume 10 25 macrocycles should be enough for effective > weight refinement in phenix, however no improvement of the R-factors. > > A quick run with default settings in competitor software 'R' yields >2% better > R-factors. > > I would appreciate suggestion how to improve my refinement protocol, values > differing from default are listed below. > > Thank you very much in advance > > Eike > > > > > > > refine { > adp { > individual { > isotropic = element H > anisotropic = not element H > } > group_adp_refinement_mode = one_adp_group_per_residue \ > *two_adp_groups_per_residue group_selection > } > } > main { > apply_overall_isotropic_scale_to_adp = False > nqh_flips = False > ordered_solvent = True > place_ions = True > number_of_macro_cycles = 10 > hydrogen_bonds = True > use_convergence_test = True > target = auto *ml mlhl ml_sad ls > random_seed = 3326496 > wavelength = 0.885611 > nproc = 4 > } > hydrogens { > refine = individual *riding Auto > } > tls { > find_automatically = False > one_residue_one_group = False > } > ordered_solvent { > mode = second_half filter_only every_macro_cycle \ > *every_macro_cycle_after_first > h_bond_min_mac = 1 > h_bond_min_sol = 1 > h_bond_max = 6 > refine_occupancies = True > new_solvent = isotropic *anisotropic > b_iso_min = 0 > } > peak_search { > max_number_of_peaks = 1303 > } > target_weights { > optimize_xyz_weight = True > optimize_adp_weight = True > wxc_scale = 0.2 > wxu_scale = 0.2

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Option for renumber the pdb
by Rojan Shrestha 28 Feb '14

28 Feb '14

Hello, I have found the program phenix.pdbtools. Maybe, it can renumber residues of pdb. I have found the options renumber_residues options but I am unable to see the options for starting residues. I have pdb starts from 1 and want to renumber 1 into 250. Can somebody tell me how to put the option for starting residue? Regards, Rojan

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scaling in phenix.fobs_minus_fobs_map
by Michael Thompson 28 Feb '14

28 Feb '14

Hello, I have a very simple question about phenix.fobs_minus_fobs_map, and it's implementation in the GUI. I just want to make sure I am not skipping an important step in generating my isomorphous difference map. I'm trying to create an Fo-Fo map for two data sets at pretty different resolutions, using phases from a model. I truncated the higher-res data so the high resolution limit matches the lower-res data set. Are these 2 mtz files sufficient for input into phenix.fobs_minus_fobs_map, or do I need to use another utility to scale the two data sets together prior to calculating the map coefficients? I suppose another way to ask my question would be, does phenix.fobs_minus_fobs_map perform scaling of the two Fobs arrays before calculating the new map? Thanks for clarifying, Mike -- Michael C. Thompson Graduate Student Biochemistry & Molecular Biology Division Department of Chemistry & Biochemistry University of California, Los Angeles miket(a)chem.ucla.edu

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problem phenix ensemble
by Firas FADEL 26 Feb '14

26 Feb '14

Hello, I am using phenix ensemble to refine an X-ray structure of a protein (40kDa) at 1.05 A in complex with a ligand. The occupancy of the ligand is 73%. After refining the structure, I found out that the program confused the position of the ligand and put some water molecules. Do you have any suggestion or a command to avoid this problem. If you need details I can send you the mtz and pdb files. Thanks in advance. Firas Fadel Firas FADEL Institut de Génétique et de Biologie Moléculaire et Cellulaire, IGBMC Equipe Alberto PODJARNY, 1 Rue Laurent Fries, 67404 Illkirch-France Email : fadel(a)igbmc.fr<mailto:[email protected]> Tel: + 33 (0) 3 88 65 33 13<tel:%2B%2033%20%280%29%203%2088%2065%2033%2013>

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Announcement: QuantumBio Release of QM-based X-ray Crystallography Plugin v1.0 for Phenix
by Lance Westerhoff 26 Feb '14

26 Feb '14

Hello All- We are pleased to announce the release of our linear scaling, quantum mechanics DivCon Discovery Suite plug-in v1.0 for the Phenix, x-ray crystallography platform. As was detailed in the recent Phenix Newsletter, when this plugin is installed, the conventional refinement functional along with the stereochemical restraints or CIFile for the ligand(s) and for the surrounding active site(s) are replaced with QM data in "real time" during the refinement in order to increase structural accuracy and decrease artificial strain. To see the full press release along with references and links for further information, please take a look at the following website: http://www.quantumbioinc.com/news/show/PhenixAnnouncement To encourage adoption, we have waived the license fee for non-profit, academic use and we have posted our commercial evaluation license as well. These licenses are available at the following link: http://www.quantumbioinc.com/products/software_licensing Certainly, let me know if you have any questions or if you would like to try out the technology on your own structures. -Lance ____________________ Lance M. Westerhoff, Ph.D. President and General Manager QuantumBio Inc. WWW: http://www.quantumbioinc.com Email: lance(a)quantumbioinc.com

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revisiting "Problem with loop fitting "
by Alejandro Buschiazzo 24 Feb '14

24 Feb '14

Dear phenix community I am attempting to use phenix.fit_loops for the first time and getting an error message: "No suitable gap found matching residues" I found a short exchange exactly about this (Jan 2011), but eventually Tom Terwilliger asked for the files directly to see if he could solve it. I can't seem to find a later summary of the solution. (apparently, the most probable reason was some kind of mismatch between PDB numbering and sequence file...which I shouldn't have... I'm probably missing some silly here - I have been fiddling around with the sequence file in many ways...with no success) many thanks for any help! alejandro -- Alejandro Buschiazzo, PhD Research Scientist Unit of Protein Crystallography Institut Pasteur de Montevideo Mataojo 2020 Montevideo 11400 URUGUAY Phone: +598 25220910 int. 120 Fax: +598 25224185 http://www.pasteur.edu.uy/pxf

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Questions about phenix.mr_rosseta
by Yonglin Hu 24 Feb '14

24 Feb '14

Hello List, I am very new to using Phenix/Rosetta to solve MR. I just finished a job by following the procedures described on phenix-online.org using Phenix GUI. The program reported that no solution was found, but when I went through the RUN_FILE_*.log, I found that despite all the log files ended with the following sentences: Stage to relax: refined_rescored_rosetta_solution No solutions to relax No autobuilt solutions to iterate... Finishing up mr_rosetta... one solution had a Rfree of 0.48 with correct number of molecules in ASU. When I refined that solution using phenix, Rfree went down further, proving to be a correct one. So my question is: why phenix.mr_rosetta did not report this solution as a good one? My second question is regarding model rebuild using phenix/rosetta. No matter I used the GUI or command lines copied from phenix-online like the following: phenix.mr_rosetta \ seq_file=~/MA/Mpa.pir \ data=~/MA/MA.mtz \ search_models=~/MA/refine_6.pdb \ already_placed=True \ fragment_files = ~/MA/MA-3mer \ fragment_files = ~/MA/MA-9mer \ rescore_mr.relax=False \ rosetta_models=20 \ ncs_copies=6 \ space_group="C 1 2 1" \ use_all_plausible_sg=False \ nproc=4 the program always fails. The log files have the following messages: Sorry, a subprocess has failed... ...... Sorry: Failed to run REBUILD...see log file in MR_ROSETTA_2/GROUP_OF_ROSETTA_REBUILD_1/RUN_1/REBUILD_IN_SETS_1/RUN_4/WORK_1/rebuild.log They pointed to rebuild.log files, but these files don't contain error message and they ended with the following seemingly innocuous lines: protocols.relax.FastRelax: CMD: accept_to_best -3682.86 0.994359 0.994359 0.44 core.scoring.rms_util: WARNING: In CA_rmsd, residue range 1 to 402 requested but only 401 protein CA atoms found. core.scoring.rms_util: WARNING: In CA_rmsd, residue range 1 to 402 requested but only 401 protein CA atoms found. protocols.relax.FastRelax: CMD: endrepeat -3682.86 0.994359 0.994359 0.44 protocols::checkpoint: Deleting checkpoints of FastRelax protocols::checkpoint: Deleting checkpoints of FastRelax protocols.jd2.JobDistributor: S_MA_R_0005 reported success in 4573 seconds protocols.jd2.JobDistributor: no more batches to process... protocols.jd2.JobDistributor: 5 jobs considered, 5 jobs attempted in 20716 seconds I would appreciate it if you could tell me what could be the causes of the failures. Thank in advance, Yonglin

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