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基本情報
登録情報 | データベース: PDB / ID: 3j4t | ||||||
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タイトル | Helical model of TubZ-Bt two-stranded filament | ||||||
![]() | FtsZ/tubulin-related protein | ||||||
![]() | STRUCTURAL PROTEIN / TubZ / FtsZ-like / tubulin-like / plasmid segregation | ||||||
機能・相同性 | plasmid partitioning / Tubulin/FtsZ, GTPase domain superfamily / 加水分解酵素; 酸無水物に作用; GTPに作用・細胞または細胞小器官の運動に関与 / GTPase activity / GTP binding / identical protein binding / metal ion binding / cytoplasm / Tubulin-like protein TubZ![]() | ||||||
生物種 | ![]() ![]() | ||||||
手法 | 電子顕微鏡法 / らせん対称体再構成法 / クライオ電子顕微鏡法 / 解像度: 10.8 Å | ||||||
![]() | Agard, D.A. / Montabana, E.A. | ||||||
![]() | ![]() タイトル: Bacterial tubulin TubZ-Bt transitions between a two-stranded intermediate and a four-stranded filament upon GTP hydrolysis. 著者: Elizabeth A Montabana / David A Agard / ![]() 要旨: Cytoskeletal filaments form diverse superstructures that are highly adapted for specific functions. The recently discovered TubZ subfamily of tubulins is involved in type III plasmid partitioning ...Cytoskeletal filaments form diverse superstructures that are highly adapted for specific functions. The recently discovered TubZ subfamily of tubulins is involved in type III plasmid partitioning systems, facilitating faithful segregation of low copy-number plasmids during bacterial cell division. One such protein, TubZ-Bt, is found on the large pBtoxis plasmid in Bacillus thuringiensis, and interacts via its extended C terminus with a DNA adaptor protein TubR. Here, we use cryo-electron microscopy to determine the structure of TubZ-Bt filaments and light scattering to explore their mechanism of polymerization. Surprisingly, we find that the helical filament architecture is remarkably sensitive to nucleotide state, changing from two-stranded to four-stranded depending on the ability of TubZ-Bt to hydrolyze GTP. We present pseudoatomic models of both the two- and four-protofilament forms based on cryo-electron microscopy reconstructions (10.8 Å and 6.9 Å, respectively) of filaments formed under different nucleotide states. These data lead to a model in which the two-stranded filament is a necessary intermediate along the pathway to formation of the four-stranded filament. Such nucleotide-directed structural polymorphism is to our knowledge an unprecedented mechanism for the formation of polar filaments. #1: ![]() 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. | ||||||
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構造の表示
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構造ビューア | 分子: ![]() ![]() |
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-検証レポート
文書・要旨 | ![]() | 766.6 KB | 表示 | ![]() |
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文書・詳細版 | ![]() | 773.3 KB | 表示 | |
XML形式データ | ![]() | 18.6 KB | 表示 | |
CIF形式データ | ![]() | 26 KB | 表示 | |
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-関連構造データ
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リンク
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集合体
登録構造単位 | ![]()
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対称性 | らせん対称: (回転対称性: 1 / Dyad axis: no / N subunits divisor: 1 / Num. of operations: 10 / Rise per n subunits: 22.048 Å / Rotation per n subunits: -168.158 °) |
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要素
#1: タンパク質 | 分子量: 55052.438 Da / 分子数: 1 / 由来タイプ: 組換発現 由来: (組換発現) ![]() ![]() 株: serovar israelensis / 遺伝子: pBt156 / プラスミド: pET151topoD / 発現宿主: ![]() ![]() |
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配列の詳細 | MUTATION L2V IS INHERITED FROM PDB ENTRY 2XKA. THE SAMPLE IMAGED FOR THIS ENTRY CONTAINS NO MUTATIONS. |
-実験情報
-実験
実験 | 手法: 電子顕微鏡法 |
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EM実験 | 試料の集合状態: FILAMENT / 3次元再構成法: らせん対称体再構成法 |
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試料調製
構成要素 | 名称: TubZ-Bt / タイプ: COMPLEX |
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緩衝液 | 名称: HMK100 / pH: 7.7 詳細: 100 mM potassium acetate, 5 mM magnesium acetate, 50 mM HEPES |
試料 | 包埋: NO / シャドウイング: NO / 染色: NO / 凍結: YES |
試料支持 | 詳細: 400 mesh copper grid with holey carbon support, glow discharged |
急速凍結 | 装置: FEI VITROBOT MARK III / 凍結剤: ETHANE / 湿度: 100 % 詳細: TubZ was preheated at 37 degrees and polymerization was initiated with saturating GTPgammaS. TubZ was then incubated for 30 seconds at room temperature before sample application, 4.5 second ...詳細: TubZ was preheated at 37 degrees and polymerization was initiated with saturating GTPgammaS. TubZ was then incubated for 30 seconds at room temperature before sample application, 4.5 second blotting, and plunge-freezing into liquid ethane (FEI VITROBOT MARK III). 手法: Blot 4.5 s before plunging |
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電子顕微鏡撮影
実験機器 | ![]() モデル: Tecnai F20 / 画像提供: FEI Company |
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顕微鏡 | モデル: FEI TECNAI F20 / 日付: 2010年5月26日 |
電子銃 | 電子線源: ![]() |
電子レンズ | モード: BRIGHT FIELD / 倍率(公称値): 62000 X / 最大 デフォーカス(公称値): 4500 nm / 最小 デフォーカス(公称値): 1500 nm / Cs: 2.2 mm |
試料ホルダ | 試料ホルダーモデル: OTHER / 資料ホルダタイプ: Oxford side-entry cryo stage |
撮影 | 電子線照射量: 20 e/Å2 フィルム・検出器のモデル: TVIPS TEMCAM-F816 (8k x 8k) 詳細: 8k x 8k |
画像スキャン | デジタル画像の数: 348 |
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解析
EMソフトウェア |
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CTF補正 | 詳細: Whole Micrograph | ||||||||||||
らせん対称 | 回転角度/サブユニット: -168.15849 ° / 軸方向距離/サブユニット: 22.04811 Å / らせん対称軸の対称性: C1 | ||||||||||||
3次元再構成 | 手法: Iterative Helical Real Space Refinement / 解像度: 10.8 Å / 解像度の算出法: FSC 0.143 CUT-OFF / ピクセルサイズ(実測値): 1.203 Å 詳細: Final map has been low-pass filtered to 11 Angstrom and high-pass filtered to 35 Angstrom. A B-factor of -452 Angstrom was applied using the program bfactor. A cylindrical mask of radius ~78 ...詳細: Final map has been low-pass filtered to 11 Angstrom and high-pass filtered to 35 Angstrom. A B-factor of -452 Angstrom was applied using the program bfactor. A cylindrical mask of radius ~78 Angstrom has been applied. 対称性のタイプ: HELICAL | ||||||||||||
原子モデル構築 | プロトコル: OTHER / 空間: REAL 詳細: METHOD--Chimera DETAILS--Just local fitting done with Chimera | ||||||||||||
原子モデル構築 | PDB-ID: 2XKA PDB chain-ID: F / Accession code: 2XKA / Source name: PDB / タイプ: experimental model | ||||||||||||
精密化ステップ | サイクル: LAST
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