Author:
Lee Juhwan,Sim Kyoung Mi,Kang Mooseok,Oh Hyun Ju,Choi Ho Jung,Kim Yeong Eun,Pack Chan-Gi,Kim Kyunggon,Kim Kyung Mo,Oh Seak Hee,Kim Inki,Chang Iksoo
Abstract
AbstractX-linked inhibitor of apoptosis protein (XIAP) deficiency causes refractory inflammatory bowel disease. The XIAP protein plays a pivotal role in the pro-inflammatory response through the nucleotide-binding oligomerization domain-containing signaling pathway that is important in mucosal homeostasis. We analyzed the molecular mechanism of non-synonymous pathogenic variants (PVs) of XIAP BIR2 domain. We generated N-terminally green fluorescent protein-tagged XIAP constructs of representative non-synonymous PVs. Co-immunoprecipitation and fluorescence cross-correlation spectroscopy showed that wild-type XIAP and RIP2 preferentially interacted in live cells, whereas all non-synonymous PV XIAPs failed to interact properly with RIP2. Structural analysis showed that various structural changes by mutations, such as hydrophobic core collapse, Zn-finger loss, and spatial rearrangement, destabilized the two loop structures (174–182 and 205–215) that critically interact with RIP2. Subsequently, it caused a failure of RIP2 ubiquitination and loss of protein deficiency by the auto-ubiquitination of all XIAP mutants. These findings could enhance our understanding of the role of XIAP mutations in XIAP-deficient inflammatory bowel disease and may benefit future therapeutic strategies.
Funder
Kun-hee Lee Child Cancer & Rare Disease Project
National Research Foundation of Korea [NRF] funded by the Ministry of Science and ICT and the Ministry of Education, Republic of Korea
Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea.
Publisher
Springer Science and Business Media LLC