Type III secretion protein HrcV / FHIPEP, domain 1 / FHIPEP conserved site / Bacterial export FHIPEP family signature. / Type III secretion system FHIPEP / FHIPEP, domain 3 / FHIPEP, domain 4 / FHIPEP family 類似検索 - ドメイン・相同性
Secretion system apparatus protein SsaV 類似検索 - 構成要素
ジャーナル: J Struct Biol / 年: 2021 タイトル: Structure of the cytoplasmic domain of SctV (SsaV) from the Salmonella SPI-2 injectisome and implications for a pH sensing mechanism. 著者: Teige R S Matthews-Palmer / Nayim Gonzalez-Rodriguez / Thomas Calcraft / Signe Lagercrantz / Tobias Zachs / Xiu-Jun Yu / Grzegorz J Grabe / David W Holden / Andrea Nans / Peter B Rosenthal / ...著者: Teige R S Matthews-Palmer / Nayim Gonzalez-Rodriguez / Thomas Calcraft / Signe Lagercrantz / Tobias Zachs / Xiu-Jun Yu / Grzegorz J Grabe / David W Holden / Andrea Nans / Peter B Rosenthal / Sarah L Rouse / Morgan Beeby / 要旨: Bacterial type III secretion systems assemble the axial structures of both injectisomes and flagella. Injectisome type III secretion systems subsequently secrete effector proteins through their ...Bacterial type III secretion systems assemble the axial structures of both injectisomes and flagella. Injectisome type III secretion systems subsequently secrete effector proteins through their hollow needle into a host, requiring co-ordination. In the Salmonella enterica serovar Typhimurium SPI-2 injectisome, this switch is triggered by sensing the neutral pH of the host cytoplasm. Central to specificity switching is a nonameric SctV protein with an N-terminal transmembrane domain and a toroidal C-terminal cytoplasmic domain. A 'gatekeeper' complex interacts with the SctV cytoplasmic domain in a pH dependent manner, facilitating translocon secretion while repressing effector secretion through a poorly understood mechanism. To better understand the role of SctV in SPI-2 translocon-effector specificity switching, we purified full-length SctV and determined its toroidal cytoplasmic region's structure using cryo-EM. Structural comparisons and molecular dynamics simulations revealed that the cytoplasmic torus is stabilized by its core subdomain 3, about which subdomains 2 and 4 hinge, varying the flexible outside cleft implicated in gatekeeper and substrate binding. In light of patterns of surface conservation, deprotonation, and structural motion, the location of previously identified critical residues suggest that gatekeeper binds a cleft buried between neighboring subdomain 4s. Simulations suggest that a local pH change from 5 to 7.2 stabilizes the subdomain 3 hinge and narrows the central aperture of the nonameric torus. Our results are consistent with a model of local pH sensing at SctV, where pH-dependent dynamics of SctV cytoplasmic domain affect binding of gatekeeper complex.
全体 : Homo-nonameric ring complex of SsaV (SctV) type III secretion sys...
全体
名称: Homo-nonameric ring complex of SsaV (SctV) type III secretion system export apparatus protein.
要素
細胞器官・細胞要素: Homo-nonameric ring complex of SsaV (SctV) type III secretion system export apparatus protein.
タンパク質・ペプチド: Secretion system apparatus protein SsaV
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超分子 #1: Homo-nonameric ring complex of SsaV (SctV) type III secretion sys...
超分子
名称: Homo-nonameric ring complex of SsaV (SctV) type III secretion system export apparatus protein. タイプ: organelle_or_cellular_component / ID: 1 / 親要素: 0 / 含まれる分子: all 詳細: Full length protein including transmembrane domain recombinantly expressed in E.coli C41 and extracted from membrane fraction with detergent DDM. Transmembrane domain present but not resolved.
由来(天然)
生物種: Salmonella enterica (サルモネラ菌) / 株: LT2
分子量
理論値: 680 KDa
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分子 #1: Secretion system apparatus protein SsaV
分子
名称: Secretion system apparatus protein SsaV / タイプ: protein_or_peptide / ID: 1 / コピー数: 1 / 光学異性体: LEVO
選択した数: 988000 詳細: interactive training particle picker in Xmipp, used in the Scipion wrapper
初期モデル
モデルのタイプ: OTHER 詳細: Ab initio 3D model generation from a balanced set of 2D views using stochastic gradient descent implemented in Relion. Initial model heavily low-pass filtered.