5ed3
crystal structure of human Hint1 complexing with AP5A
Structural highlights
FunctionHINT1_HUMAN Hydrolyzes adenosine 5'-monophosphoramidate substrates such as AMP-morpholidate, AMP-N-alanine methyl ester, AMP-alpha-acetyl lysine methyl ester and AMP-NH2 (By similarity). Publication Abstract from PubMedSignal transduction systems enable organisms to monitor their external environments and accordingly adjust the cellular processes. In mast cells, the second messenger Ap4A binds to the histidine triad nucleotide-binding protein 1 (HINT1), disrupts its interaction with the microphthalmia-associated transcription factor (MITF), and eventually activates the transcription of genes downstream of MITF in response to immunostimulation. How the HINT1 protein recognizes and is regulated by Ap4A remain unclear. Here, using eight crystal structures, biochemical experiments, negative stain electron microscopy, and cellular experiments, we report that Ap4A specifically polymerizes HINT1 in solution and in activated rat basophilic leukemia cells. The polymerization interface overlaps with the area on HINT1 for MITF interaction, suggesting a possible competitive mechanism to release MITF for transcriptional activation. The mechanism depends precisely on the length of the phosphodiester linkage of Ap4A. These results highlight a direct polymerization signaling mechanism by the second messenger. Second messenger Ap4A polymerizes target protein HINT1 to transduce signals in FcepsilonRI-activated mast cells.,Yu J, Liu Z, Liang Y, Luo F, Zhang J, Tian C, Motzik A, Zheng M, Kang J, Zhong G, Liu C, Fang P, Guo M, Razin E, Wang J Nat Commun. 2019 Oct 11;10(1):4664. doi: 10.1038/s41467-019-12710-8. PMID:31604935[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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