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Need program for breaking symmetry in cryo-EM reconstruction of icosahedral particles

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I have a dataset of cryo-EM image projections of an icosahedral virus. The virus has a tiny density stemming from exiting RNA at one particular site. When running a 3D reconstruction with RELION by using icosaedral averaging this density disappears because it is too weak as it is spread out over 60 equivalent sites. When running the same dataset without icosaedral averaging I get a highly distorted volume because it now coresponds to 60 fold less particles.

I thus want to run a reconstruction minimizing the cross correlation between the images only allowing rotations given by the rotation matrix of the icosaedron. That means I allow no translations and only 60 sets of the 3 angles defining icosadrally equivalent orientations.

I am looking for somebody being able to program such a routine that is known as 'symmetry breaking' It appears to be implemented in EMAN2 but is not in RELION neither in XMIPP.

Sorry if this question was posted twice because I was not familiar with the procedure!
asked Oct 20, 2014 in Image analysis by blaas (140 points)

1 Answer

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Hello blaas,

I think this is a very specific question and is better discussed in person. Please contact me directly manuel.pasieka@csf.ac.at and lets arange a meeting.

regards,

Manuel
answered Oct 21, 2014 by pasieka (220 points)
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