8W71

Structural basis of chorismate isomerization by Arabidopsis isochorismate synthase ICS1

Summary for 8W71

• Entry DOI: 10.2210/pdb8w71/pdb
• Descriptor: Isochorismate synthase 1, chloroplastic, (3R,4R)-3-[(1-carboxyethenyl)oxy]-4-hydroxycyclohexa-1,5-diene-1-carboxylic acid, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: chorismate-bound atics1 complex, isomerase
• Biological source: Arabidopsis thaliana (thale cress)
• Total number of polymer chains: 2
• Total formula weight: 119044.53

Authors

Su, Z.H.,Ming, Z.H. (deposition date: 2023-08-30, release date: 2024-05-22, Last modification date: 2024-10-16)

Primary citation

Su, Z.,Niu, C.,Zhou, S.,Xu, G.,Zhu, P.,Fu, Q.,Zhang, Y.,Ming, Z.
Structural basis of chorismate isomerization by Arabidopsis ISOCHORISMATE SYNTHASE1.
Plant Physiol., 196:773-787, 2024

PubMed Abstract: Salicylic acid (SA) plays a crucial role in plant defense against biotrophic and semi-biotrophic pathogens. In Arabidopsis (Arabidopsis thaliana), isochorismate synthase 1 (AtICS1) is a key enzyme for the pathogen-induced biosynthesis of SA via catalytic conversion of chorismate into isochorismate, an essential precursor for SA synthesis. Despite the extensive knowledge of ICS1-related menaquinone, siderophore, tryptophan (MST) enzymes in bacteria, the structural mechanisms for substrate binding and catalysis in plant isochorismate synthase (ICS) enzymes are unknown. This study reveals that plant ICS enzymes catalyze the isomerization of chorismate through a magnesium-dependent mechanism, with AtICS1 exhibiting the most substantial catalytic activity. Additionally, we present high-resolution crystal structures of apo AtICS1 and its complex with chorismate, offering detailed insights into the mechanisms of substrate recognition and catalysis. Importantly, our investigation indicates the existence of a potential substrate entrance channel and a gating mechanism regulating substrate into the catalytic site. Structural comparisons of AtICS1 with MST enzymes suggest a shared structural framework with conserved gating and catalytic mechanisms. This work provides valuable insights into the structural and regulatory mechanisms governing substrate delivery and catalysis in AtICS1, as well as other plant ICS enzymes.

PubMed: 38701037
DOI: 10.1093/plphys/kiae260

Experimental method

X-RAY DIFFRACTION (2.121 Å)