ジャーナル: Proc Natl Acad Sci U S A / 年: 2013 タイトル: Structure and assembly of an inner membrane platform for initiation of type IV pilus biogenesis. 著者: Vijaykumar Karuppiah / Richard F Collins / Angela Thistlethwaite / Ya Gao / Jeremy P Derrick / 要旨: Type IV pili are long fibers that are assembled by polymerization of a major pilin protein in the periplasm of a wide range of bacteria and archaea. They play crucial roles in pathogenesis, DNA ...Type IV pili are long fibers that are assembled by polymerization of a major pilin protein in the periplasm of a wide range of bacteria and archaea. They play crucial roles in pathogenesis, DNA transformation, and motility, and are capable of rapid retraction, generating powerful motor forces. PilN and PilO are integral inner membrane proteins that are essential for type IV pilus formation. Here, we show that PilN and PilO from Thermus thermophilus can be isolated as a complex with PilM, a cytoplasmic protein with structural similarities to the cytoskeletal protein MreB. The crystal structure of the periplasmic portion of PilN forms a homodimer with an extensive, conserved interaction interface. We conducted serial 3D reconstructions by electron microscopy of PilMN, PilMNO, and PilMNO bound to the major pilin protein PilA4, to chart the assembly of the inner membrane pilus biogenesis platform. PilN drives the dimerization of the PilMN complex with a stoichiometry of 2:2; binding of two PilO monomers then causes the PilN periplasmic domains to dissociate. Finally, two PilA4 monomers bind to the periplasmic domains of PilN and PilO, to generate a T-shaped complex that is primed for addition of the pilin to the nascent pilus fiber. Docking of structures for PilM, PilN, PilO, and PilA4 into the electron density maps of the transmembrane complexes was used to generate a sequence of molecular structures that chart the initial events in type IV pilus formation, and provide structural information on the early events in this important secretion process.
CYTOPLASMIC AND TRANSMEMBRANE REGIONS REMOVED. THE FIRST FOUR RESIDUES (GSHM) AT THE N-TERMINUS AND ...CYTOPLASMIC AND TRANSMEMBRANE REGIONS REMOVED. THE FIRST FOUR RESIDUES (GSHM) AT THE N-TERMINUS AND THE LAST EIGHT RESIDUES (LEHHHHHH) ARE FROM THE EXPRESSION VECTOR
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実験情報
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実験
実験
手法: X線回折 / 使用した結晶の数: 1
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試料調製
結晶
マシュー密度: 1.8 Å3/Da / 溶媒含有率: 32 % / 解説: NONE
結晶化
pH: 7 詳細: 0.1 M HEPES PH 7.0 0.2 M MAGNESIUM CHLORIDE 20% PEG 6000 10 MM ZINC CHLORIDE
プロトコル: SINGLE WAVELENGTH / 単色(M)・ラウエ(L): M / 散乱光タイプ: x-ray
放射波長
波長: 0.969 Å / 相対比: 1
反射
解像度: 2.05→40 Å / Num. obs: 20669 / % possible obs: 99.4 % / Observed criterion σ(I): 2 / 冗長度: 3.4 % / Rmerge(I) obs: 0.07 / Net I/σ(I): 12.9
反射 シェル
解像度: 2.05→2.1 Å / 冗長度: 3.4 % / Rmerge(I) obs: 0.57 / Mean I/σ(I) obs: 2.4 / % possible all: 98.8
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解析
ソフトウェア
名称
バージョン
分類
REFMAC
5.6.0117
精密化
XDS
データ削減
PHENIX
位相決定
精密化
構造決定の手法: 単波長異常分散 開始モデル: NONE 解像度: 2.05→47.96 Å / Cor.coef. Fo:Fc: 0.945 / Cor.coef. Fo:Fc free: 0.928 / SU B: 3.6 / SU ML: 0.099 / 交差検証法: THROUGHOUT / ESU R: 0.158 / ESU R Free: 0.145 / 立体化学のターゲット値: MAXIMUM LIKELIHOOD / 詳細: HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS.
Rfactor
反射数
%反射
Selection details
Rfree
0.22623
1058
5.1 %
RANDOM
Rwork
0.19584
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obs
0.19733
19607
99.38 %
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溶媒の処理
イオンプローブ半径: 0.8 Å / 減衰半径: 0.8 Å / VDWプローブ半径: 1.2 Å / 溶媒モデル: MASK