Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Disorder-to-order active site capping regulates the rate-limiting step of the inositol pathway
Δημιουργός/Συγγραφέας:	Träger, Toni K Kyrilis, Fotis L Hamdi, Farzad Tüting, Christian Alfes, Marie Hofmann, Tommy Schmidt, Carla [EL] Καστρίτης, Παναγιώτης[EN] Kastritis, Panagiotis
Ημερομηνία:	2024-08-20
Γλώσσα:	Αγγλικά
ISSN:	0027-8424 1091-6490
DOI:	10.1073/pnas.2400912121
Άλλο:	39145930
Περίληψη:	Myo-inositol-1-phosphate synthase (MIPS) catalyzes the NAD+-dependent isomerization of glucose-6-phosphate (G6P) into inositol-1-phosphate (IMP), controlling the rate-limiting step of the inositol pathway. Previous structural studies focused on the detailed molecular mechanism, neglecting large-scale conformational changes that drive the function of this 240 kDa homotetrameric complex. In this study, we identified the active, endogenous MIPS in cell extracts from the thermophilic fungus Thermochaetoides thermophila. By resolving the native structure at 2.48 Å (FSC = 0.143), we revealed a fully populated active site. Utilizing 3D variability analysis, we uncovered conformational states of MIPS, enabling us to directly visualize an order-to-disorder transition at its catalytic center. An acyclic intermediate of G6P occupied the active site in two out of the three conformational states, indicating a catalytic mechanism where electrostatic stabilization of high-energy intermediates plays a crucial role. Examination of all isomerases with known structures revealed similar fluctuations in secondary structure within their active sites. Based on these findings, we established a conformational selection model that governs substrate binding and eventually inositol availability. In particular, the ground state of MIPS demonstrates structural configurations regardless of substrate binding, a pattern observed across various isomerases. These findings contribute to the understanding of MIPS structure-based function, serving as a template for future studies targeting regulation and potential therapeutic applications.
Τίτλος πηγής δημοσίευσης:	Proceedings of the National Academy of Sciences of the United States of America
Τόμος/Κεφάλαιο:	121
Τεύχος:	34
Θεματική Κατηγορία:	[EL] Δομική Βιολογία[EN] Structural Biology [EL] Φασματοσκοπία[EN] Spectroscopy [EL] Εφαρμοσμένη οπτική. Φωτονική[EN] Applied optics. Photonics [EL] Βιοχημεία[EN] Biochemistry [EL] Μικροβιολογία[EN] Microbiology
Λέξεις-Κλειδιά:	endogenous cryo-EM induced fit inositol metabolism conformational selection
EU Grant:	hot4cryo BMBF, ZIK program
EU Grant identifier:	101086665 03Z22HN23 03Z22HI2 03COV04 03Z22HN22 ZS/2016/04/78115 391498659 RTG 2467
Κάτοχος πνευματικών δικαιωμάτων:	© 2024 the Author(s). Published by PNAS
Όροι και προϋποθέσεις δικαιωμάτων:	This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY).
Ηλεκτρονική διεύθυνση στον εκδότη (link):	https://doi.org/10.1073/pnas.2400912121
Σημειώσεις:	This article contains supporting information online at https://doi.org/10.1073/pnas.2400912121#supplementary-materials
Εμφανίζεται στις συλλογές:	Ινστιτούτο Χημικής Βιολογίας - Επιστημονικό έργο