An electron microscopic study of the archaeal feast/famine regulatory protein: 4. Estimation of the particle size

Using the method of Fourier transform, cryo-electron micrographs of two types of archaeal feast/famine regulatory proteins (FFRPs), pot0434017 (FL11) and pot1216151 (DM1), were analyzed. After correcting the Fourier power spectra by considering effects of the contrast transfer functions (CTFs), peak...

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Bibliographic Details
Published in:Proceedings of the Japan Academy, Series B Series B, 2004, Vol.80(3), pp.148-155
Main Authors: CLOWNEY, Lester, ISHIJIMA, Sanae A., SUZUKI, Masashi
Format: Article
Language:English
Subjects:
Archaea
Contrast transfer function
cryo-electron microscopy
Fourier analysis
hyper-thermophile
image processing
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Summary:Using the method of Fourier transform, cryo-electron micrographs of two types of archaeal feast/famine regulatory proteins (FFRPs), pot0434017 (FL11) and pot1216151 (DM1), were analyzed. After correcting the Fourier power spectra by considering effects of the contrast transfer functions (CTFs), peaks were identified at frequencies, corresponding to the particle size of ~130 Å for FL11 in the complex with DNA, in addition, a smaller size, ~40 Å for the same protein in the absence of DNA, the particle size of ~65 Å for DM1 when interacting with a ligand, and a smaller size of ~30 Å when the ligand was removed. These numbers are consistent with our previous observations that dimers of FL11 form octamers, i.e. tetrameric assemblies of the dimers, upon intercation with DNA, and that similar octamers of a smaller FFRP, DM1 of the molecular weight approximately half that of FL11, are stabilized by interaction with the ligand. Some aspects of CTF correction are discussed. (Communicated by Masanori OTSUKA, M.J.A.)
ISSN:0386-2208
1349-2896
DOI:10.2183/pjab.80.148