Dear Andy,

Best would be to convert the phaser angles (plus vector) in a matrix (plus 
vector) and use this for your transformations. The phaser people should be able 
to provide you with information how to do this, since they have to do it in 
order to produce their output files. Alternatively, you may try to find a 
transformation program which takes phaser angles as an input. I do have some 
prehistoric subroutines which do all kind of conversions between angles and 
matrices, and if nothing works, I could have a look if one of those subroutines 
could to the job.

Best,
Herman

Von: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] Im Auftrag von Andrew 
Lovering
Gesendet: Mittwoch, 9. Januar 2019 17:08
An: CCP4BB@JISCMAIL.AC.UK
Betreff: [EXTERNAL] [ccp4bb] complex multi-crystal averaging

Dear All,

I suspect the way out of this is a new crystal (!) but interested to hear any 
advice.

I have two crystal forms of a 500aa protein, vaguely tube-shaped

1=P3121, diffracts to 4.1 ang, 3 copies in asu, 86% solvent; map indicates it 
is a relative of other folds (but those are not so close that they'd be a good 
guide to sequence register). I have selenomet SAD phases which helps identify 
Met positions. The 3-fold and high solvent give a great map but you wouldn't 
want to build it and buccanner and phenix think similar

2=I222, 2 copies per asu, 66% solvent. This has a cell that gives wildly 
anisotropic diffraction - ~3, 3.5, 4.3 down different axes. Not really 
rectified by staraniso. No phases

So I can cut the density out of form 1 map (using secondary structure elements 
of a rough PDB as a mask), and use phaser with this density as search model to 
find the two copies with a TFZ of about 10. The phaser map shows a bit of 
detail and the solution has placed the protomers such that they agree with a 
self-rotation function. Phenix find_ncs on phaser map similarly agrees (as I 
would expect).

Now...I have an eye on multi-crystal averaging between the two forms. BUT the 
phaser map isn't good enough to manually place the PDB used in cut-out density, 
and I can't see a straightforward way of using the angle info in phaser sol to 
perform a co-ordinate transformation (but I think ccp4bb users will put me 
right on this - I'd imagine placing the PDB into the cutout density mtz then 
using PDBset?). I tried converting the phaser mtz to a map using FFT then using 
phased TF in Molrep to place the PDB but this didn't work, complaining about 
the grid used.

One last caveat - I have multiple sets for the I222 that intriguingly differ by 
12 angstrom down a 240 ang axis: doing multi-crystal averaging between  these 
two forms achieves little when I would expect otherwise (all the NCS 
correlations are good, high initial agreement)

Like I said...fingers crossed for a new crystal form!

Andy





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