Biotechnology and Biological Sciences Research Council (BBSRC)
英国
引用
ジャーナル: Proc Natl Acad Sci U S A / 年: 2025 タイトル: Subunit specialization in AAA+ proteins and substrate unfolding during transcription complex remodeling. 著者: Forson Gao / Fuzhou Ye / Martin Buck / Xiaodong Zhang / 要旨: Bacterial RNA polymerase (RNAP) is a multisubunit enzyme that copies DNA into RNA in a process known as transcription. Bacteria use σ factors to recruit RNAP to promoter regions of genes that need ...Bacterial RNA polymerase (RNAP) is a multisubunit enzyme that copies DNA into RNA in a process known as transcription. Bacteria use σ factors to recruit RNAP to promoter regions of genes that need to be transcribed, with 60% bacteria containing at least one specialized σ factor, σ. σ recruits RNAP to promoters of genes associated with stress responses and forms a stable closed complex that does not spontaneously isomerize to the open state where promoter DNA is melted out and competent for transcription. The σ-mediated open complex formation requires specific AAA+ proteins (TPases ssociated with diverse cellular ctivities) known as bacterial enhancer-binding proteins (bEBPs). We have now obtained structures of new intermediate states of bEBP-bound complexes during transcription initiation, which elucidate the mechanism of DNA melting driven by ATPase activity of bEBPs and suggest a mechanistic model that couples the Adenosine triphosphate (ATP) hydrolysis cycle within the bEBP hexamer with σ unfolding. Our data reveal that bEBP forms a nonplanar hexamer with the hydrolysis-ready subunit located at the furthest/highest point of the spiral hexamer relative to the RNAP. ATP hydrolysis induces conformational changes in bEBP that drives a vectoral transiting of the regulatory N terminus of σ into the bEBP hexamer central pore causing the partial unfolding of σ, while forming specific bEBP contacts with promoter DNA. Furthermore, our data suggest a mechanism of the bEBP AAA+ protein that is distinct from the hand-over-hand mechanism proposed for many other AAA+ proteins, highlighting the versatile mechanisms utilized by the large protein family.
全体 : Subtracted refinement map of conformation 1 of PspF(1-275)-sigma5...
全体
名称: Subtracted refinement map of conformation 1 of PspF(1-275)-sigma54 bound to nifH DNA (-28 to +35) containing mismatch from -11 to -8.
要素
複合体: Subtracted refinement map of conformation 1 of PspF(1-275)-sigma54 bound to nifH DNA (-28 to +35) containing mismatch from -11 to -8.
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超分子 #1: Subtracted refinement map of conformation 1 of PspF(1-275)-sigma5...
超分子
名称: Subtracted refinement map of conformation 1 of PspF(1-275)-sigma54 bound to nifH DNA (-28 to +35) containing mismatch from -11 to -8. タイプ: complex / ID: 1 / 親要素: 0 / 含まれる分子: #1-#12
由来(天然)
生物種: Escherichia coli K-12 (大腸菌)
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実験情報
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構造解析
手法
クライオ電子顕微鏡法
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
緩衝液
pH: 8
凍結
凍結剤: ETHANE
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電子顕微鏡法
顕微鏡
TFS KRIOS
撮影
フィルム・検出器のモデル: GATAN K3 BIOQUANTUM (6k x 4k) 平均電子線量: 50.0 e/Å2