ジャーナル: J Biol Chem / 年: 2012 タイトル: The hexameric structure of a conjugative VirB4 protein ATPase provides new insights for a functional and phylogenetic relationship with DNA translocases. 著者: Alejandro Peña / Inmaculada Matilla / Jaime Martín-Benito / José M Valpuesta / José L Carrascosa / Fernando de la Cruz / Elena Cabezón / Ignacio Arechaga / 要旨: VirB4 proteins are ATPases essential for pilus biogenesis and protein transport in type IV secretion systems. These proteins contain a motor domain that shares structural similarities with the motor ...VirB4 proteins are ATPases essential for pilus biogenesis and protein transport in type IV secretion systems. These proteins contain a motor domain that shares structural similarities with the motor domains of DNA translocases, such as the VirD4/TrwB conjugative coupling proteins and the chromosome segregation pump FtsK. Here, we report the three-dimensional structure of full-length TrwK, the VirB4 homologue in the conjugative plasmid R388, determined by single-particle electron microscopy. The structure consists of a hexameric double ring with a barrel-shaped structure. The C-terminal half of VirB4 proteins shares a striking structural similarity with the DNA translocase TrwB. Docking the atomic coordinates of the crystal structures of TrwB and FtsK into the EM map revealed a better fit for FtsK. Interestingly, we have found that like TrwB, TrwK is able to bind DNA with a higher affinity for G4 quadruplex structures than for single-stranded DNA. Furthermore, TrwK exerts a dominant negative effect on the ATPase activity of TrwB, which reflects an interaction between the two proteins. Our studies provide new insights into the structure-function relationship and the evolution of these DNA and protein translocases.
分子 #1: VirB4 component of type IV transporter system
分子
名称: VirB4 component of type IV transporter system / タイプ: protein_or_peptide / ID: 1 / Name.synonym: VirB4 / 集合状態: Hexamer / 組換発現: Yes
由来(天然)
生物種: Escherichia coli (大腸菌)
分子量
理論値: 540 KDa
組換発現
生物種: Escherichia coli (大腸菌) / 組換プラスミド: pET
配列
GO: ATP binding InterPro: CagE, TrbE, VirB component of type IV transporter system
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実験情報
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構造解析
手法
ネガティブ染色法
解析
単粒子再構成法
試料の集合状態
particle
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試料調製
濃度
0.1 mg/mL
緩衝液
pH: 6.45 詳細: 50 mM PIPES-NaOH, 75 mM potassium acetate, 5% (w/v) glycerol, 10 mM magnesium acetate, 0.1 mM EDTA, and 0.5 mM phenylmethylsulfonyl fluoride.
染色
タイプ: NEGATIVE 詳細: Samples were negatively stained with 2% (w/v) uranyl acetate
グリッド
詳細: freshly glow-discharged carbon-coated grids
凍結
凍結剤: NONE / 装置: OTHER
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電子顕微鏡法
顕微鏡
JEOL 1200EXII
日付
2011年12月11日
撮影
カテゴリ: FILM / フィルム・検出器のモデル: KODAK SO-163 FILM / デジタル化 - スキャナー: ZEISS SCAI / 平均電子線量: 20 e/Å2