Structural highlights
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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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