February 2023 - phenixbb - phenix-online.org

map deposition strategy after density modification
by Daniel Larsson 20 Sep '23

20 Sep '23

Hi Phenix community, I’ve been using density modification with some success for my data and am considering the most appropriate way to do model building/refinement and then deposition of my results. Here are some questions/observations: 1) Which map should I refine against (most importantly, do the final minimization using phenix.real_space_refine)? The DM map is the most clear one, so I’m favoring to do it against this one (as long as the geometry/validation is also best for this one). 2) Which map should I deposit as my main map? Is it the autosharpened one or the DM one? Since the DM map looks the best, I want the user who only downloads one map to see this one, so again I favoring this map. 3) Which nominal resolution should I quote for my reconstruction? Since the procedure seems to introduce correlation between the two maps (see point 4 below), it does not seem to be possible to obtain a gold-standard FSC value between two truly independent half-maps. As the DM procedure supposedly actually improves the map (by leveraging knowledge about what solvent and macromolecular maps usually looks like and thereby improves the Fourier coefficients), it feels like it would be misrepresenting the data by quoting the FSC_0.143 from the original reconstruction. Should I use the FSC_0.5 estimated value that phenix.resolve_cryo_em outputs? 4) Which FSC curve should I deposit? When I calculate the FSC between the two density modified half-maps, I get a funny (or rather not so funny) looking curve with a bump at around 3Å and it does not go to zero at Nyquist (which does not agree with the map quality). This must again be due to the induced correlation between the maps, presumably during the masking of solvent and macromolecule density. Phenix.resolve_cryo_em calculates a FSC curve to calculate the FSC_0.5 value, which according to the manual page corrects for the correlation induced between the two maps: "Density modification introduces some correlations between half-maps due to solvent flattening. This can have a small effect on the resolution estimates obtained with half-map FSC. The resolution estimates provided by the program are corrected for this effect." But is this curve good enough? I think OneDeposit wants to have the gold-standard FSC curve, right? 5) Which (nowadays mandatory) half-maps should one deposit? Here I would say that the original half-maps before DM makes more sense, since these are less processed. But if one specify these as the half-maps, there will be inconsistencies during validation, since the DM map will look quite different from the average between the two original half-maps. Also the automatic FSC curve will be very different from the deposited one. So in conclusion, despite what I say above, the most conservative thing would be to deposit the conventionally sharpened map as my main map and use the original half-maps for calculating the FSC-curve and use the 0.143 threshold from this curve to estimate the resolution. The DM map can be used during rebuilding/refinement, but I think final minimization should be against the main map during deposition (with restraints if the geometry gets worse). The DM map can be deposited as an auxiliary map. Do the community and the developers agree? Regards, Daniel När du har kontakt med oss på Uppsala universitet med e-post så innebär det att vi behandlar dina personuppgifter. För att läsa mer om hur vi gör det kan du läsa här: http://www.uu.se/om-uu/dataskydd-personuppgifter/ E-mailing Uppsala University means that we will process your personal data. For more information on how this is performed, please read here: http://www.uu.se/en/about-uu/data-protection-policy

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Two postdoctoral positions at CNB-CSIC, Spain
by Carmen San Martin 23 Feb '23

23 Feb '23

Dear all, Please find here information on two open positions on structural biology / protein design: https://saco.csic.es/index.php/s/gFm9EKLMNBWD2G8 Regards, ------------------------------------------------------------- Carmen San Martín, Ph. D. Centro Nacional de Biotecnología (CNB-CSIC) Darwin, 3 28049-Madrid (SPAIN) Email: carmen(a)cnb.csic.es Phone: 34-91-5855450 (internal: 432228) Fax: 34-91-5854506 <http://www.cnb.csic.es/> http://wwwuser.cnb.csic.es/~sanmartinlab http://www.microscopia.org ------------------------------------------------------------

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Macromolecular Crystallography School in Madrid from the 8th to the 12th of May 2023
by Armando Albert 20 Feb '23

20 Feb '23

Dear all, The registration for the next edition of the Macromolecular Crystallography School in Madrid from the 8th to the 12th of May 2023 is open. The workshop has been organized at Instituto de Química Física Rocasolano CSIC since 2010 and it is meant for 25 graduate students or researchers with previous expertise in crystallography and/or CryoEM who need a deeper insight into the most advanced crystallographic and CryoEM techniques to carry out their research projects. The program traditionally covers aspects such as sample preparation, structure solution, model building, crystallographic refinement, validation, and analysis of the structural results, as well as an overview of the newest structural biology technologies. On top of these subjects, this year's program will include those aspects related to the impact of Artificial Intelligence methods on structure solution and low-resolution refinement. In addition, we will cover dynamic crystallography at XFEL and synchrotron and ligand building for drug discovery. You may find further information on our website (https://www.xtal.iqfr.csic.es/MCCS2023/index.html <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fwww.xtal.iqfr.csic.es%2…>) Hoping to see you In Madrid Juan and Armando Armando Albert and Juan A. Hermoso Departamento de Cristalografía y Biología Estructural Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas Serrano 119, 28006 Madrid Spain

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(no subject)
by Armando Albert 06 Feb '23

06 Feb '23

Dear all, The registration for the next edition of the Macromolecular Crystallography School in Madrid from the 8th to the 12th of May 2023 is open. The workshop has been organized at Instituto de Química Física Rocasolano CSIC since 2010 and it is meant for 25 graduate students or researchers with previous expertise in crystallography and/or CryoEM who need a deeper insight into the most advanced crystallographic and CryoEM techniques to carry out their research projects. The program traditionally covers aspects such as sample preparation, structure solution, model building, crystallographic refinement, validation, and analysis of the structural results, as well as an overview of the newest structural biology technologies. On top of these subjects, this year's program will include those aspects related to the impact of Artificial Intelligence methods on structure solution and low-resolution refinement. In addition, we will cover dynamic crystallography at XFEL and synchrotron and ligand building for drug discovery. You may find further information on our website (https://www.xtal.iqfr.csic.es/MCCS2023/index.html <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fwww.xtal.iqfr.csic.es%2…>) Hoping to see you In Madrid Juan and Armando Armando Albert and Juan A. Hermoso Departamento de Cristalografía y Biología Estructural Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas Serrano 119, 28006 Madrid Spain

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Solving MR solution without sequence information
by Rosenberg, Eric (NIH/NCI) [F] 06 Feb '23

06 Feb '23

Hi all, I'm in a bit of bind here and am seeking some advice. For context, a former graduate student in our lab set crystal trays of an MBP fusion protein, the fused part after MBP being ~400 amino acids long. This region is also predicted to be mostly unstructured, but has a C-terminal SH3 domain. Our graduate student then graduated and before throwing out some of her trays a year or two later, we found some hits of the MBP fusion protein that actually diffracted to 2.9 Angstrom. I spent some time working on it after we collected the data (June 2021), but because I didn't know what crystallized specifically, it was impossible to phase, and replicating seemed next to impossible, too. The Matthew's coefficient was predicting ~130 amino acids in the ASU, space group C222 or C2221. Since whatever crystallized was clearly a degradation product of the MBP fusion, I tried phasing with SH3 domains and a lot of other things to no avail. As a final last ditch effort I eventually submitted the .mtz file to SBGrid to perform a Wide Search MR job, and low and behold it actually found MR solutions that had TFZ scores ~17 in space group C2221! So here's my current situation-I have been able to phase the data set using the MR search model, but again, I don't know what specifically it is that I've crystallized. I'm currently able to get the Rfree to ~0.4, but can't seem to improve it. I am really at a loss of what to do, since there are obvious backbone issues with the protein (as seen from iterative build composite omit maps), but every time I try to manually correct them it seems to make the Rfree worse. The MR solution does not align very well at all to the MBP fusion, only ~20 identity, and again, I don't know to which ~130 amino acids I crystallized out of the ~400 of the MBP fusion. Is it one continuous stretch, two copies of a shorter stretch, etc.? I tried phasing with a polyalanine model of the MR search model and then tried autobuilding just a polyalanine sequence to get the backbone right, but that doesn't seem to work. Autobuild also fails when trying to various fragments of the MBP fusion sequence. Other than opening coot and manually building the entire polypeptide chain, is there an easier method? I think that once the backbone is totally right the phases will improve so I can start putting in side chains, but I'm not sure. My latest effort is to just use Sculptor prior to Phaser in order to force the sequences to match, but again, I don't know precisely what sequence was crystallized. I have tried both the Phenix and CCP4 software suites, for reference. Any and all help would be much appreciated (and yield an acknowledgement on a paper, if this ever works). Best, Eric Rosenberg CRTA Postdoctoral Fellow Randazzo Lab Laboratory of Cellular and Molecular Biology National Cancer Institute, US

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Re: [phenixbb] Solving MR solution without sequence information
by Dom Bellini 04 Feb '23

04 Feb '23

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Re: [phenixbb] Solving MR solution without sequence information
by Kay Diederichs 03 Feb '23

03 Feb '23

Hi Eric, I'd try the following: 1) use SIMBAD to potentially find other/better models 2) use ISOLDE for model building - maybe ask Tristan Croll for help 3) submit your best model to the DALI server to retrieve closer models HTH, Kay -- Kay Diederichs http://strucbio.biologie.uni-konstanz.de email: Kay.Diederichs(a)uni-konstanz.de Tel +49 7531 88 4049 Fachbereich Biologie, Universität Konstanz, Box M647, D-78457 Konstanz This e-mail is digitally signed. If your e-mail client does not have the necessary capabilities, just ignore the attached signature "smime.p7s".

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