1G24

THE CRYSTAL STRUCTURE OF EXOENZYME C3 FROM CLOSTRIDIUM BOTULINUM

1G24 の概要

• エントリーDOI: 10.2210/pdb1g24/pdb
• 関連するPDBエントリー: 1QS1 1QS2
• 分子名称: EXOENZYME C3 (2 entities in total)
• 機能のキーワード: c3, adp-ribosyltransferase, transferase
• 由来する生物種: Clostridium botulinum
• 細胞内の位置: Secreted: P15879
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 94367.88

構造登録者

Han, S.,Arvai, A.S.,Clancy, S.B.,Tainer, J.A. (登録日: 2000-10-16, 公開日: 2000-12-18, 最終更新日: 2023-08-09)

主引用文献

Han, S.,Arvai, A.S.,Clancy, S.B.,Tainer, J.A.
Crystal structure and novel recognition motif of rho ADP-ribosylating C3 exoenzyme from Clostridium botulinum: structural insights for recognition specificity and catalysis.
J.Mol.Biol., 305:95-107, 2001

PubMed Abstract: Clostridium botulinum C3 exoenzyme inactivates the small GTP-binding protein family Rho by ADP-ribosylating asparagine 41, which depolymerizes the actin cytoskeleton. C3 thus represents a major family of the bacterial toxins that transfer the ADP-ribose moiety of NAD to specific amino acids in acceptor proteins to modify key biological activities in eukaryotic cells, including protein synthesis, differentiation, transformation, and intracellular signaling. The 1.7 A resolution C3 exoenzyme structure establishes the conserved features of the core NAD-binding beta-sandwich fold with other ADP-ribosylating toxins despite little sequence conservation. Importantly, the central core of the C3 exoenzyme structure is distinguished by the absence of an active site loop observed in many other ADP-ribosylating toxins. Unlike the ADP-ribosylating toxins that possess the active site loop near the central core, the C3 exoenzyme replaces the active site loop with an alpha-helix, alpha3. Moreover, structural and sequence similarities with the catalytic domain of vegetative insecticidal protein 2 (VIP2), an actin ADP-ribosyltransferase, unexpectedly implicates two adjacent, protruding turns, which join beta5 and beta6 of the toxin core fold, as a novel recognition specificity motif for this newly defined toxin family. Turn 1 evidently positions the solvent-exposed, aromatic side-chain of Phe209 to interact with the hydrophobic region of Rho adjacent to its GTP-binding site. Turn 2 evidently both places the Gln212 side-chain for hydrogen bonding to recognize Rho Asn41 for nucleophilic attack on the anomeric carbon of NAD ribose and holds the key Glu214 catalytic side-chain in the adjacent catalytic pocket. This proposed bipartite ADP-ribosylating toxin turn-turn (ARTT) motif places the VIP2 and C3 toxin classes into a single ARTT family characterized by analogous target protein recognition via turn 1 aromatic and turn 2 hydrogen-bonding side-chain moieties. Turn 2 centrally anchors the catalytic Glu214 within the ARTT motif, and furthermore distinguishes the C3 toxin class by a conserved turn 2 Gln and the VIP2 binary toxin class by a conserved turn 2 Glu for appropriate target side-chain hydrogen-bonding recognition. Taken together, these structural results provide a molecular basis for understanding the coupled activity and recognition specificity for C3 and for the newly defined ARTT toxin family, which acts in the depolymerization of the actin cytoskeleton. This beta5 to beta6 region of the toxin fold represents an experimentally testable and potentially general recognition motif region for other ADP-ribosylating toxins that have a similar beta-structure framework.

PubMed: 11114250
DOI: 10.1006/jmbi.2000.4292

実験手法

X-RAY DIFFRACTION (1.7 Å)