we had a P1 case with 12 mols/au, about 30% sequence id, 2.4A
resolution, which was solved after a lot of trials with phaser. Other
problems of these crystals were that they took months to grow and
invariable presented multiple lattices (we did not try microbeam).
See:
Crystallization of the avian reovirus double-stranded RNA-binding and
core protein sigmaA.
Hermo-Parrado XL, Guardado-Calvo P, Llamas-Saiz AL, Fox GC,
Vazquez-Iglesias L, Martínez-Costas J, Benavente J, van Raaij MJ.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2007 May 1;63(Pt
5):426-9. Epub 2007 Apr 20. PMID: 17565188
Crystal structure of the avian reovirus inner capsid protein sigmaA.
Guardado-Calvo P, Vazquez-Iglesias L, Martinez-Costas J, Llamas-Saiz
AL, Schoehn G, Fox GC, Hermo-Parrado XL, Benavente J, van Raaij MJ.
J Virol. 2008 Nov;82(22):11208-16. Epub 2008 Sep 17. PMID: 18799570
Quoting Mario Milani <[log in to unmask]>:
> Thank you for the suggestions. The data resolution is 1.9 so i can try
> different heavy atoms techniques ... anyway i am really puzzled by the
> peculiar assembly in the crystal and on the possible causes... does anyone
> know about similar cases?
> mario
>
>>
>> Mario,
>> beside what you were mentioning, I would definitely try a quick soak
>> (10-30 seconds) of the crystals in cryo conditions supplemented with
>> halides such as NaBr, or NaI, at pretty high concentrations (say 0.5 M),
>> then directly freezing without backsoak.
>> If the crystals survive the treatment, with that amount of mols per unit
>> cells and surely some good NCS, you should be able to phase pretty easily.
>> Well, of course SeMet would be the other option...
>> ciao,
>> s
>>
>> On Sep 30, 2010, at 1:54 PM, Mario Milani wrote:
>>
>>> Dear all,
>>> i have a 30 kDa protein that crystallize so far in three different
>>> conditions but with the same space group. It initially looks like
>>> tetragonal (I4, a=141, b=141, c=208) and then results triclinic (P1,
>>> a=141, b=141 c=144, alpha=119, beta=119, gamma=90), hosting about 24
>>> mol. in the unit cell. Other data: self rotation shows the presence of 4
>>> peaks with chi=180; molecular replacement shows the presence of a
>>> pseudo-translation peak; DLS made at protein concentration close to
>>> crystal growth conditions shows a Rh compatible with something like a
>>> tetramer with low polydispersity (about 15%). Do you have any experience
>>> with similar ‘asymmetric’ associations? Do you have any suggestions,
>>> beside the addition of ligands to the crystal growth conditions, in
>>> order to get a ‘simpler’ crystallographic assembly? I have some models
>>> (with sequence identity less than 25%) in order to try MR but all trials
>>> so far did not solve the structure (using balbes, molrep, phaser and
>>> epmr). Any suggestion is welcome.
>>> Thank you,
>>>
>>> Mario Milani
>>
>>
>> --
>> Sebastiano Pasqualato, PhD
>> IFOM-IEO Campus
>> Dipartimento di Oncologia Sperimentale
>> Istituto Europeo di Oncologia
>> via Adamello, 16
>> 20139 - Milano
>> Italy
>>
>> tel +39 02 9437 5094
>> fax +39 02 9437 5990
>>
>>
>
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