The structure of NAD+consuming proteinAcinetobacter baumanniiTIR domain shows unique kinetics and conformations Article Swipe
YOU?
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· 2023
· Open Access
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· DOI: https://doi.org/10.1101/2023.05.19.541320
· OA: W4377194928
Toll-like and Interleukin-1/18 receptor resistance (TIR) domain-containing proteins function as important signaling and immune regulatory molecules. TIR domain-containing proteins identified in eukaryotic and prokaryotic species also exhibit NAD+ hydrolase activity in select bacteria, plants, and mammalian cells. We report the crystal structure of the Acinetobacter baumannii TIR domain protein (AbTir-TIR) with confirmed NAD + hydrolysis and map the conformational effects of its interaction with NAD + using HDX-MS. NAD + results in mild decreases in deuterium uptake at the dimeric interface. In addition, AbTir-TIR exhibits EX1 kinetics indicative of large cooperative conformational changes which are slowed down upon substrate binding. Additionally, we have developed label-free imaging using 2pFLIM which shows differences in bacteria expressing native and mutant NAD+ hydrolase-inactivated AbTir-TIR EA protein. Our observations are consistent with substrate-induced conformational changes reported in other TIR model systems with NAD+ hydrolase activity. These studies provide further insight into bacterial TIR protein mechanisms and their varying roles in biology.
