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bioRxiv · 10.1101/2020.08.13.250241

Structural and biochemical mechanisms of NLRP1 inhibition by DPP9

Chai, J.·Zhong, F. L.·Huang, M.·zhang, X.·Wang, J.·Wu, B.·Han, Z.·Ann, T. G.·Gong, Q.
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Abstract

The nucleotide-binding domain (NBD) and leucine-rich repeat (LRR)-containing receptors (NLRs) mediate innate immunity by forming inflammasomes. Activation of the NLR protein NLRP1 requires auto-cleavage within its FIIND domain1-7. In resting cells, the dipeptidyl peptidase DPP9 interacts with NLRP1-FIIND and together with a related enzyme DPP8, suppresses spontaneous NLRP1 activation8,9. The mechanisms of DPP8/9-mediated NLRP1 inhibition, however, remain elusive. Here we provide structural and biochemical evidence demonstrating that rat NLRP1 (rNLRP1) interacts with rDPP9 in a stepwise manner to form a 2:1 complex. An auto-inhibited rNLRP1 molecule first interacts with rDPP9 via its ZU5 domain. This 1:1 rNLRP1-rDPP9 complex then captures the UPA domain of a second rNLRP1 molecule via a UPA-interacting site on DPP9 and dimeric UPA-UPA interactions with the first rNLRP1. The 2:1 rNLRP1-rDPP9 complex prevents NLRP1 UPA-mediated higher order oligomerization and maintains NLRP1 in the auto-inhibited state. Structure-guided biochemical and functional assays show that both NLRP1-binding and its enzymatic activity are required for DPP9 to suppress NLRP1, supporting guard-type activation of the NLR. Together, our data reveal the mechanism of DPP9-mediated inhibition of NLRP1 and shed light on activation of the NLRP1 inflammasome.

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Chai, J., Zhong, F. L., Huang, M., zhang, X., Wang, J., Wu, B., Han, Z., Ann, T. G., Gong, Q.. 2020-08-14. Structural and biochemical mechanisms of NLRP1 inhibition by DPP9. https://doi.org/10.1101/2020.08.13.250241

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