Hi Randy, what about implementing the use of EM-models (e.g. structure factors from EM model) in Phenix to carry out MR and/or MR-SAD? There's a growing number of macromolecular complexes that have been imaged at medium/low res by EM, which could be of great help to phase at low res or located anomalous scatterers in phased maps. And the EM database keeps growing! At this moment, it is certainly possible to use EM models in Phaser, but the Phenix pipeline could add much more to that. For instance, Phenix would allow for better phase extension of low res EM phases to higher res by ncs-averaging or multi-crystal averaging (in Resolve). Or Phenix could help combining low res EM phases with other phase sources such as SeMet sites, poorly occupied heavy atom sites, etc (MR-SAD). Or Phenix could rigid body refine (at low resolution) pseudo-atomic models obtained by filling in EM-models with dummy atoms. This would help defining averaging masks and so on. What do you think? Thanks in advance, Gino *********************************************************** Gino Cingolani, Ph.D. Assistant Professor Dept. of Biochemistry and Molecular Biology SUNY Upstate Medical University 750 E. Adams Street, Syracuse, NY, 13210 Tel. (315) 464 8744 Fax. (315) 464 8750 Email: [email protected] *********************************************************** "Nati non foste per viver come bruti, ma per seguir virtute e conoscenza" ("You were not born to live like brutes, but to follow virtue and knowledge") Dante, The Divine Comedy (Inferno, XXVI, vv. 119-120)
Hi, As it happens, we've been working very hard over the last few months first to make all commands in Phaser available from Python (done) and second to make all options available from the new Phenix GUI (getting close). ("We" in this context mostly means Airlie at our end and Nat at the Berkeley end.) So it should become easy to switch to using density instead of coordinates for your models without switching to the command-line mode of running Phaser. We're also very interested in optimizing the way that we use density from EM, which is something we haven't spent enough time playing with yet. It's not yet possible to use density for a model in the MR-SAD mode--that's been on the wish list and shouldn't be too hard. Do you need that feature right now? I really like your other ideas, so we'll have to talk to Tom about adapting the AutoMR wizard so that it doesn't require a coordinate file. As you say, this will be a real growth area! All the best, Randy On 8 May 2009, at 15:39, Gino Cingolani wrote:
Hi Randy,
what about implementing the use of EM-models (e.g. structure factors from EM model) in Phenix to carry out MR and/or MR-SAD? There's a growing number of macromolecular complexes that have been imaged at medium/low res by EM, which could be of great help to phase at low res or located anomalous scatterers in phased maps. And the EM database keeps growing!
At this moment, it is certainly possible to use EM models in Phaser, but the Phenix pipeline could add much more to that. For instance, Phenix would allow for better phase extension of low res EM phases to higher res by ncs-averaging or multi-crystal averaging (in Resolve). Or Phenix could help combining low res EM phases with other phase sources such as SeMet sites, poorly occupied heavy atom sites, etc (MR-SAD). Or Phenix could rigid body refine (at low resolution) pseudo-atomic models obtained by filling in EM-models with dummy atoms. This would help defining averaging masks and so on. What do you think?
Thanks in advance,
Gino
*********************************************************** Gino Cingolani, Ph.D. Assistant Professor Dept. of Biochemistry and Molecular Biology SUNY Upstate Medical University 750 E. Adams Street, Syracuse, NY, 13210 Tel. (315) 464 8744 Fax. (315) 464 8750 Email: [email protected] *********************************************************** "Nati non foste per viver come bruti, ma per seguir virtute e conoscenza" ("You were not born to live like brutes, but to follow virtue and knowledge") Dante, The Divine Comedy (Inferno, XXVI, vv. 119-120) _______________________________________________ phenixbb mailing list [email protected] http://www.phenix-online.org/mailman/listinfo/phenixbb
------ Randy J. Read Department of Haematology, University of Cambridge Cambridge Institute for Medical Research Tel: + 44 1223 336500 Wellcome Trust/MRC Building Fax: + 44 1223 336827 Hills Road E-mail: [email protected] Cambridge CB2 0XY, U.K. www- structmed.cimr.cam.ac.uk
Hi Gino, I think that we should be able to modify the AutoMR wizard to take density maps instead of models. I'll work with Randy and Airlie and Nat to do this. -Tom T Thomas C. Terwilliger Mail Stop M888 Los Alamos National Laboratory Los Alamos, NM 87545 Tel: 505-667-0072 email: [email protected] Fax: 505-665-3024 SOLVE web site: http://solve.lanl.gov PHENIX web site: http:www.phenix-online.org ISFI Integrated Center for Structure and Function Innovation web site: http://techcenter.mbi.ucla.edu TB Structural Genomics Consortium web site: http://www.doe-mbi.ucla.edu/TB CBSS Center for Bio-Security Science web site: http://www.lanl.gov/cbss On May 11, 2009, at 2:24 AM, Randy Read wrote:
Hi,
As it happens, we've been working very hard over the last few months first to make all commands in Phaser available from Python (done) and second to make all options available from the new Phenix GUI (getting close). ("We" in this context mostly means Airlie at our end and Nat at the Berkeley end.) So it should become easy to switch to using density instead of coordinates for your models without switching to the command-line mode of running Phaser. We're also very interested in optimizing the way that we use density from EM, which is something we haven't spent enough time playing with yet. It's not yet possible to use density for a model in the MR-SAD mode--that's been on the wish list and shouldn't be too hard. Do you need that feature right now?
I really like your other ideas, so we'll have to talk to Tom about adapting the AutoMR wizard so that it doesn't require a coordinate file. As you say, this will be a real growth area!
All the best,
Randy
On 8 May 2009, at 15:39, Gino Cingolani wrote:
Hi Randy,
what about implementing the use of EM-models (e.g. structure factors from EM model) in Phenix to carry out MR and/or MR-SAD? There's a growing number of macromolecular complexes that have been imaged at medium/low res by EM, which could be of great help to phase at low res or located anomalous scatterers in phased maps. And the EM database keeps growing!
At this moment, it is certainly possible to use EM models in Phaser, but the Phenix pipeline could add much more to that. For instance, Phenix would allow for better phase extension of low res EM phases to higher res by ncs-averaging or multi-crystal averaging (in Resolve). Or Phenix could help combining low res EM phases with other phase sources such as SeMet sites, poorly occupied heavy atom sites, etc (MR-SAD). Or Phenix could rigid body refine (at low resolution) pseudo-atomic models obtained by filling in EM-models with dummy atoms. This would help defining averaging masks and so on. What do you think?
Thanks in advance,
Gino
*********************************************************** Gino Cingolani, Ph.D. Assistant Professor Dept. of Biochemistry and Molecular Biology SUNY Upstate Medical University 750 E. Adams Street, Syracuse, NY, 13210 Tel. (315) 464 8744 Fax. (315) 464 8750 Email: [email protected] *********************************************************** "Nati non foste per viver come bruti, ma per seguir virtute e conoscenza" ("You were not born to live like brutes, but to follow virtue and knowledge") Dante, The Divine Comedy (Inferno, XXVI, vv. 119-120) _______________________________________________ phenixbb mailing list [email protected] http://www.phenix-online.org/mailman/listinfo/phenixbb
------ Randy J. Read Department of Haematology, University of Cambridge Cambridge Institute for Medical Research Tel: + 44 1223 336500 Wellcome Trust/MRC Building Fax: + 44 1223 336827 Hills Road E-mail: [email protected] Cambridge CB2 0XY, U.K. www- structmed.cimr.cam.ac.uk
_______________________________________________ phenixbb mailing list [email protected] http://www.phenix-online.org/mailman/listinfo/phenixbb
Hi Gino, Tom and Randy, I would rather argue for a future "specialized" phenix low res molecular replacement application/wizard than for simple conversion to throw an EM map into a standard MR procedure. In my experience, MR with EM models is significantly more complex than with a molecular model for several reasons. For example, - the EM maps may suffer from scaling errors which can have a severe impact on packing function scores and downstream averaging procedures, so an automatic "scale grid search" would be really useful. - EM maps sometimes are affected by accumulation of density along axes of symmetry of particles which can severely bias the outcome. Sometimes grid searches for the origin of symmetry combined with initial low-res averaging steps are helpful. - Maps without an associated molecular model are difficult to break into conformationally rigid parts. Although many EM structures are derived on the basis of conformational classification or sorting, this information is not usually presented in a useful way in publications or database depositions. - Negative stain (cryo) EM maps are particular prone to conformation distortions due to staining artifacts. - For particles with strongly preferred orientations on the EM grid, the maps may have some special features - ... A preferred application for (low-res) MR from EM maps ( or also SAXS data ???) would ideally be able to solve some of these problems. A plain density to structure factor conversion as an entry to standard MR can already easily be done manually. But if it's done automatically without overcoming the above problems, many research will once try "automated MR from EM" through wizard X. If this ends unsuccessfully, they may believe their problem could simply not be solved and feel discouraged from investing a little more time and finally miss a chance to solve their problems. Cheers, Timm Dr. Timm Maier ETH Zurich Institute of Molecular Biology and Biophysics HPK H 5 Schafmattstr. 20 8093 Zurich SWITZERLAND e-mail: [email protected] phone ++41 44 633 3148
participants (4)
-
Gino Cingolani -
Maier Timm -
Randy Read -
Tom Terwilliger