EMDB/PDB/SASBDBから引用されている文献のデータベース

キーワード
構造解析手法	All X線回折 NMR 電子顕微鏡小角散乱中性子線回折線維回折粉末回折赤外分光 EPR FRET 理論モデルハイブリッド
著者・登録者
ジャーナル
IF	>30 >20 >10 >5 all

タイトル	Structures of the peptidase-containing ABC transporter PCAT1 under equilibrium and nonequilibrium conditions.
ジャーナル・号・ページ	Proc Natl Acad Sci U S A, Vol. 119, Issue 4, Year 2022
掲載日	2022年1月25日
著者	Virapat Kieuvongngam / Jue Chen /
PubMed 要旨	ATP-binding cassette (ABC) transporters are ubiquitous molecular pumps that transport a broad range of substrates across biological membranes. Although the structure and function of ABC transporters ...ATP-binding cassette (ABC) transporters are ubiquitous molecular pumps that transport a broad range of substrates across biological membranes. Although the structure and function of ABC transporters has been studied extensively, our understanding of their energetics and dynamics remains limited. Here, we present studies of the peptidase-containing ABC transporter 1 (PCAT1), a polypeptide processing and secretion ABC transporter that functions via the classic alternating access mechanism. PCAT1 is a homodimer containing two peptidase (PEP) domains, two transmembrane domains, and two nucleotide-binding domains (NBDs). Using cryo-electron microscopy, we analyzed the structures of wild-type PCAT1 under conditions that either prevent or permit ATP hydrolysis and observed two completely different conformational distributions. In the presence of ATP but absence of Mg, PCAT1 adopts an NBD-dimerized, outward-facing conformation. The two PEP domains are dissociated from the transporter core, preventing uncoupled substrate cleavage. The addition of Mg to promote ATP hydrolysis shifts the majority of the particles into NBD-separated, inward-facing conformations. Under this ATP turnover condition, only a small fraction of PCAT1 adopts the NBD-dimerized conformation. These data give rise to two mechanistic conclusions: 1) the ATP-bound, NBD-dimerized conformation is the lowest energy state, and 2) the rate-limiting step in the PCAT1 transport cycle is the formation of the NBD dimer. The thermodynamic conclusion is likely a general property shared by many ABC transporters. The kinetic bottleneck, however, varies from transporter to transporter.
リンク	Proc Natl Acad Sci U S A / PubMed:35074919 / PubMed Central
手法	EM (単粒子)
解像度	3.7 - 4.5 Å
構造データ	25694 7t54 EMDB-25694, PDB-7t54: Cryo-EM structure of ATP-bound PCAT1 in the outward-facing conformation 手法: EM (単粒子) / 解像度: 4.5 Å 25695 7t55 EMDB-25695, PDB-7t55: Cryo-EM structure of PCAT1 in the inward-facing wide conformation under ATP turnover condition 手法: EM (単粒子) / 解像度: 4.1 Å 25696 7t56 EMDB-25696, PDB-7t56: Cryo-EM structure of PCAT1 in the inward-facing intermediate conformation under ATP turnover condition 手法: EM (単粒子) / 解像度: 3.7 Å 25697 7t57 EMDB-25697, PDB-7t57: Cryo-EM structure of PCAT1 in the inward-facing narrow conformation under ATP turnover condition 手法: EM (単粒子) / 解像度: 3.7 Å
化合物	ChemComp-ATP: ADENOSINE-5'-TRIPHOSPHATE / ATP / ATP, エネルギー貯蔵分子YM ChemComp-MG*: Unknown entry / マグネシウムジカチオン
由来	acetivibrio thermocellus (バクテリア)
キーワード	TRANSPORT PROTEIN / ATP-binding cassette / ABC transporter / protein transport