ジャーナル: Nature / 年: 2006 タイトル: Structure of the E. coli signal recognition particle bound to a translating ribosome. 著者: Christiane Schaffitzel / Miro Oswald / Imre Berger / Takashi Ishikawa / Jan Pieter Abrahams / Henk K Koerten / Roman I Koning / Nenad Ban / 要旨: The prokaryotic signal recognition particle (SRP) targets membrane proteins into the inner membrane. It binds translating ribosomes and screens the emerging nascent chain for a hydrophobic signal ...The prokaryotic signal recognition particle (SRP) targets membrane proteins into the inner membrane. It binds translating ribosomes and screens the emerging nascent chain for a hydrophobic signal sequence, such as the transmembrane helix of inner membrane proteins. If such a sequence emerges, the SRP binds tightly, allowing the SRP receptor to lock on. This assembly delivers the ribosome-nascent chain complex to the protein translocation machinery in the membrane. Using cryo-electron microscopy and single-particle reconstruction, we obtained a 16 A structure of the Escherichia coli SRP in complex with a translating E. coli ribosome containing a nascent chain with a transmembrane helix anchor. We also obtained structural information on the SRP bound to an empty E. coli ribosome. The latter might share characteristics with a scanning SRP complex, whereas the former represents the next step: the targeting complex ready for receptor binding. High-resolution structures of the bacterial ribosome and of the bacterial SRP components are available, and their fitting explains our electron microscopic density. The structures reveal the regions that are involved in complex formation, provide insight into the conformation of the SRP on the ribosome and indicate the conformational changes that accompany high-affinity SRP binding to ribosome nascent chain complexes upon recognition of the signal sequence.
全体 : E. coli ribosome nascent chain complexes and signal recognition p...
全体
名称: E. coli ribosome nascent chain complexes and signal recognition particle
要素
試料: E. coli ribosome nascent chain complexes and signal recognition particle
複合体: E.coli 70S ribosome
RNA: A-site tRNA
RNA: P-site tRNA
RNA: E-site tRNA
リガンド: E. coli SRP
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超分子 #1000: E. coli ribosome nascent chain complexes and signal recognition p...
超分子
名称: E. coli ribosome nascent chain complexes and signal recognition particle タイプ: sample / ID: 1000 / 集合状態: One SRP binds to one ribosome. / Number unique components: 5
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超分子 #1: E.coli 70S ribosome
超分子
名称: E.coli 70S ribosome / タイプ: complex / ID: 1 / 組換発現: No / Ribosome-details: ribosome-prokaryote: ALL
由来(天然)
生物種: Escherichia coli (大腸菌)
分子量
理論値: 2.5 MDa
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分子 #1: A-site tRNA
分子
名称: A-site tRNA / タイプ: rna / ID: 1 / 分類: TRANSFER / Structure: DOUBLE HELIX / Synthetic?: No
由来(天然)
生物種: Escherichia coli (大腸菌)
分子量
理論値: 25 KDa
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分子 #2: P-site tRNA
分子
名称: P-site tRNA / タイプ: rna / ID: 2 / 分類: TRANSFER / Structure: DOUBLE HELIX / Synthetic?: No
由来(天然)
生物種: Escherichia coli (大腸菌)
分子量
理論値: 25 KDa
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分子 #3: E-site tRNA
分子
名称: E-site tRNA / タイプ: rna / ID: 3 / 分類: TRANSFER / Structure: DOUBLE HELIX / Synthetic?: No