ジャーナル: Nat Commun / 年: 2025 タイトル: Cryo-EM Structure of the relaxosome, a complex essential for bacterial mating and the spread of antibiotic resistance genes. 著者: Sunanda M Williams / Sandra Raffl / Sabine Kienesberger / Aravindan Ilangovan / Ellen L Zechner / Gabriel Waksman / 要旨: Bacterial mating, or conjugation, was discovered nearly 80 years ago as a process transferring genes from one bacterial cell (the donor) to another (the recipient). It requires three key multiprotein ...Bacterial mating, or conjugation, was discovered nearly 80 years ago as a process transferring genes from one bacterial cell (the donor) to another (the recipient). It requires three key multiprotein complexes in the donor cell: a DNA-processing machinery called the relaxosome, a double-membrane spanning type 4 secretion system (T4SS), and an extracellular appendage termed pilus. While the near-atomic resolution structures of the T4SS and pilus are already known, that of the relaxosome has not been reported to date. Here, we describe the cryo-EM structure of the fully assembled relaxosome encoded by the paradigm F plasmid in two different states corresponding to distinct functional steps along the DNA processing reaction. By varying the structures of model DNAs we delineate conformational changes required to initiate conjugation. Mutational studies of the various protein-protein and protein-DNA interaction hubs suggest a complex sensitive to trigger signals, that could arise from cell-to-cell contacts with recipient cells.
全体 : Complex of the relaxosome containing oriT DNA, accessory proteins...
全体
名称: Complex of the relaxosome containing oriT DNA, accessory proteins TraY and TraM, host protein IHF and truncated relaxase TraI1-863
要素
複合体: Complex of the relaxosome containing oriT DNA, accessory proteins TraY and TraM, host protein IHF and truncated relaxase TraI1-863
複合体: Heteroduplex OriT DNA containing the nic site
DNA: T-strand DNA (96-MER)
DNA: R-strand DNA (85-MER)
複合体: IHF heterodimer
タンパク質・ペプチド: Integration host factor subunit alpha
タンパク質・ペプチド: Integration host factor subunit beta
複合体: Train of three TraY proteins
タンパク質・ペプチド: Relaxosome protein TraY
複合体: Relaxase/helicase protein TraI1-863 with active helicase and C-terminal domains deleted.
タンパク質・ペプチド: Multifunctional conjugation protein TraI
複合体: TraM tetramer
リガンド: MAGNESIUM ION
+
超分子 #1: Complex of the relaxosome containing oriT DNA, accessory proteins...
超分子
名称: Complex of the relaxosome containing oriT DNA, accessory proteins TraY and TraM, host protein IHF and truncated relaxase TraI1-863 タイプ: complex / ID: 1 / 親要素: 0 / 含まれる分子: #1-#6
+
超分子 #2: Heteroduplex OriT DNA containing the nic site
超分子
名称: Heteroduplex OriT DNA containing the nic site / タイプ: complex / ID: 2 / 親要素: 1 / 含まれる分子: #1-#2 詳細: Prepared by annealing of chemically synthesised oligos
名称: Train of three TraY proteins / タイプ: complex / ID: 4 / 親要素: 1 / 含まれる分子: #5
由来(天然)
生物種: Escherichia coli K-12 (大腸菌)
+
超分子 #5: Relaxase/helicase protein TraI1-863 with active helicase and C-te...
超分子
名称: Relaxase/helicase protein TraI1-863 with active helicase and C-terminal domains deleted. タイプ: complex / ID: 5 / 親要素: 1 / 含まれる分子: #6
由来(天然)
生物種: Escherichia coli K-12 (大腸菌)
+
超分子 #6: TraM tetramer
超分子
名称: TraM tetramer / タイプ: complex / ID: 6 / 親要素: 1 詳細: Used for complex formation, but density was excluded from the local refinement. TraM is therefore not present in the model
由来(天然)
生物種: Escherichia coli K-12 (大腸菌)
+
分子 #1: T-strand DNA (96-MER)
分子
名称: T-strand DNA (96-MER) / タイプ: dna / ID: 1 / コピー数: 1 / 分類: DNA
解像度のタイプ: BY AUTHOR / 解像度: 3.42 Å / 解像度の算出法: FSC 0.143 CUT-OFF / 使用した粒子像数: 165577
初期 角度割当
タイプ: MAXIMUM LIKELIHOOD / 詳細: CryoSPARC ab-initio
最終 角度割当
タイプ: MAXIMUM LIKELIHOOD / 詳細: Local refinement
FSC曲線 (解像度の算出)
-
原子モデル構築 1
精密化
プロトコル: AB INITIO MODEL
得られたモデル
PDB-9f0z: CryoEM structure of the F plasmid relaxosome with truncated TraI1-863 in its TE mode, derived from the ss-27_+8ds+9_+143-R_deltaAH+CTD Locally-refined 3.42 A Map