7TZO

The apo structure of human mTORC2 complex

Summary for 7TZO

• Entry DOI: 10.2210/pdb7tzo/pdb
• EMDB information: 26213
• Descriptor: Serine/threonine-protein kinase mTOR, Target of rapamycin complex subunit LST8, Rapamycin-insensitive companion of mTOR, ... (4 entities in total)
• Functional Keywords: complex, signaling protein
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 8
• Total formula weight: 1189814.63

Authors

Yu, Z.,Chen, J.,Pearce, D. (deposition date: 2022-02-16, release date: 2023-01-11, Last modification date: 2024-06-12)

Primary citation

Yu, Z.,Chen, J.,Takagi, E.,Wang, F.,Saha, B.,Liu, X.,Joubert, L.M.,Gleason, C.E.,Jin, M.,Li, C.,Nowotny, C.,Agard, D.,Cheng, Y.,Pearce, D.
Interactions between mTORC2 core subunits Rictor and mSin1 dictate selective and context-dependent phosphorylation of substrate kinases SGK1 and Akt.
J.Biol.Chem., 298:102288-102288, 2022

PubMed Abstract: Mechanistic target of rapamycin complex 2 (mTORC2) is a multi-subunit kinase complex, central to multiple essential signaling pathways. Two core subunits, Rictor and mSin1, distinguish it from the related mTORC1 and support context-dependent phosphorylation of its substrates. mTORC2 structures have been determined previously; however, important questions remain, particularly regarding the structural determinants mediating substrate specificity and context-dependent activity. Here, we used cryo-EM to obtain high-resolution structures of the human mTORC2 apo-complex in the presence of substrates Akt and SGK1. Using functional assays, we then tested predictions suggested by substrate-induced structural changes in mTORC2. For the first time, we visualized in the apo-state the side chain interactions between Rictor and mTOR that sterically occlude recruitment of mTORC1 substrates and confer resistance to the mTORC1 inhibitor rapamycin. Also in the apo-state, we observed that mSin1 formed extensive contacts with Rictor via a pair of short α-helices nestled between two Rictor helical repeat clusters, as well as by an extended strand that makes multiple weak contacts with Rictor helical cluster 1. In co-complex structures, we found that SGK1, but not Akt, markedly altered the conformation of the mSin1 N-terminal extended strand, disrupting multiple weak interactions while inducing a large rotation of mSin1 residue Arg-83, which then interacts with a patch of negatively charged residues within Rictor. Finally, we demonstrate mutation of Arg-83 to Ala selectively disrupts mTORC2-dependent phosphorylation of SGK1, but not of Akt, supporting context-dependent substrate selection. These findings provide new structural and functional insights into mTORC2 specificity and context-dependent activity.

PubMed: 35926713
DOI: 10.1016/j.jbc.2022.102288

Experimental method

ELECTRON MICROSCOPY (3.28 Å)