کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2186827 1096082 2009 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Electron Microscopic Evidence in Support of α-Solenoid Models of Proteasomal Subunits Rpn1 and Rpn2
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی بیولوژی سلول
پیش نمایش صفحه اول مقاله
Electron Microscopic Evidence in Support of α-Solenoid Models of Proteasomal Subunits Rpn1 and Rpn2
چکیده انگلیسی

Rpn1 (109 kDa) and Rpn2 (104 kDa) are components of the 19S regulatory complex of the proteasome. The central portions of both proteins are predicted to have toroidal α-solenoid folds composed of 9–11 proteasome/cyclosome repeats, each ∼ 40 residues long and containing two α-helices and turns [A. V. Kajava, J. Biol. Chem. 277, 49791-49798, 2002]. To evaluate this prediction, we examined the full-length yeast proteins and truncated versions thereof consisting only of the repeat-containing regions by gel filtration, CD spectroscopy, and negative-staining electron microscopy (EM). All four proteins are monomeric in solution and highly α-helical, particularly the truncated ones. The EM data were analyzed by image classification and averaging techniques. The preponderant projections, in each case, show near-annular molecules 6–7 nm in diameter. Comparison of the full-length with the truncated proteins showed molecules similar in size and shape, indicating that their terminal regions are flexible and thus smeared to invisibility in the averaged images. We tested the toroidal model further by calculating resolution-limited projections and comparing them with the EM images. The results support the α-solenoid model, except that they indicate that the repeats are organized not as symmetrical circular toroids but in less regular horseshoe-like structures.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Biology - Volume 386, Issue 5, 13 March 2009, Pages 1204–1211
نویسندگان
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