6rae
Structural analysis of the Salmonella type III secretion system ATPase InvC
Structural highlights
FunctionSCTN1_SALTY ATPase component of the type III secretion system (T3SS), also called injectisome, which is used to inject bacterial effector proteins into eukaryotic host cells (PubMed:15060043, PubMed:16208377, PubMed:26170413). Acts as a molecular motor to provide the energy that is required for the export of proteins (Probable). Required for type III secretion apparatus (T3SA) formation, proper protein secretion, host cell invasion and virulence (PubMed:8045880, PubMed:14762212, PubMed:15060043, PubMed:26170413). May play a critical role in T3SS substrate recognition, disassembly of the effector/chaperone complex and unfolding of the effector in an ATP-dependent manner prior to secretion (PubMed:16208377). Releases the effector protein SptP from the chaperone SicP in an ATP-dependent manner (PubMed:16208377).[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedTranslocation of virulence effector proteins through the type III secretion system (T3SS) is essential for the virulence of many medically relevant Gram-negative bacteria. The T3SS ATPases are conserved components that specifically recognize chaperone-effector complexes and energize effector secretion through the system. It is thought that functional T3SS ATPases assemble into a cylindrical structure maintained by their N-terminal domains. Using SEC-MALS and native mass spectrometry, we show that in the absence of the N-terminal oligomerization domain the Salmonella T3SS ATPase InvC can form monomers and dimers in solution. We also present for the first time a 2.05 a resolution crystal structure of InvC lacking the oligomerization domain (InvCDelta79) and map the amino acids suggested for ATPase intersubunit interaction, binding to other T3SS proteins and chaperone-effector recognition. Furthermore, we validate the InvC ATP binding site by co-crystallization of InvCDelta79 with ATPgammaS (2.65 a) and ADP (2.80 a). Upon ATP-analogue recognition, these structures reveal remodeling of the ATP-binding site and conformational changes of two loops located outside of the catalytic site. Both loops face the central pore of the predicted InvC cylinder and are essential for the function of the T3SS ATPase. Our results present a fine functional and structural correlation of InvC and provide further details of the homo-oligomerization process and ATP-dependent conformational changes underlying the T3SS ATPase activity. This article is protected by copyright. All rights reserved. Structural analysis of ligand-bound states of the Salmonella type III secretion system ATPase InvC.,Bernal I, Romermann J, Flacht L, Lunelli M, Uetrecht C, Kolbe M Protein Sci. 2019 Aug 8. doi: 10.1002/pro.3704. PMID:31393998[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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