ジャーナル: Proc Natl Acad Sci U S A / 年: 2010 タイトル: Filament structure of bacterial tubulin homologue TubZ. 著者: Christopher H S Aylett / Qing Wang / Katharine A Michie / Linda A Amos / Jan Löwe / 要旨: Low copy number plasmids often depend on accurate partitioning systems for their continued survival. Generally, such systems consist of a centromere-like region of DNA, a DNA-binding adaptor, and a ...Low copy number plasmids often depend on accurate partitioning systems for their continued survival. Generally, such systems consist of a centromere-like region of DNA, a DNA-binding adaptor, and a polymerizing cytomotive filament. Together these components drive newly replicated plasmids to opposite ends of the dividing cell. The Bacillus thuringiensis plasmid pBToxis relies on a filament of the tubulin/FtsZ-like protein TubZ for its segregation. By combining crystallography and electron microscopy, we have determined the structure of this filament. We explain how GTP hydrolysis weakens the subunit-subunit contact and also shed light on the partitioning of the plasmid-adaptor complex. The double helical superstructure of TubZ filaments is unusual for tubulin-like proteins. Filaments of ParM, the actin-like partitioning protein, are also double helical. We suggest that convergent evolution shapes these different types of cytomotive filaments toward a general mechanism for plasmid separation.
pH: 7.5 / 詳細: 50 mM NaHEPES 7.5 150 mM KCl 5 mM MgCl2 1 mM GTPyS
染色
タイプ: NEGATIVE / 詳細: 1% Uranyl Acetate
グリッド
詳細: CuRh 300 mesh
凍結
凍結剤: NONE / 装置: OTHER
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電子顕微鏡法
顕微鏡
FEI TECNAI 12
温度
平均: 293 K
撮影
カテゴリ: CCD / フィルム・検出器のモデル: KODAK SO-163 FILM
電子線
加速電圧: 120 kV / 電子線源: TUNGSTEN HAIRPIN
電子光学系
照射モード: FLOOD BEAM / 撮影モード: BRIGHT FIELD / 倍率(公称値): 69000
試料ステージ
試料ホルダー: Eucentric / 試料ホルダーモデル: SIDE ENTRY, EUCENTRIC
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画像解析
最終 再構成
想定した対称性 - らせんパラメータ - 軸対称性: C2 (2回回転対称) アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 35.0 Å / 解像度の算出法: OTHER / ソフトウェア - 名称: MRC 詳細: Final maps were calculated from five averaged datasets