Recently, the novel coronavirus (SARS-CoV-2), which has spread from China to the world, was declared a global public health emergency, which causes lethal respiratory infections. Acetylation of several proteins plays essential roles in various biological processes, such as viral infections. We reported that the nucleoproteins of influenza virus and Zaire Ebolavirus were acetylated, suggesting that these modifications contributed to the molecular events involved in viral replication. Similar to influenza virus and Ebolavirus, the coronavirus also contains single-stranded RNA, as its viral genome interacts with the nucleocapsid (N) proteins. In this study, we report that SARS-CoV and SARS-CoV-2 N proteins are strongly acetylated by human histone acetyltransferases, P300/CBP-associated factor (PCAF), and general control nonderepressible 5 (GCN5), but not by CREB-binding protein (CBP)
in vitro
. Liquid chromatography-mass spectrometry analyses identified 2 and 12 acetyl-lysine residues from SARS-CoV and SARS-CoV-2 N proteins, respectively. Particularly in the SARS-CoV-2 N proteins, the acetyl-lysine residues were localized in or close to several functional sites, such as the RNA interaction domains and the M-protein interacting site. These results suggest that acetylation of SARS-CoV-2 N proteins plays crucial roles in their functions.
In eukaryotes, CREB-binding protein (CBP), a coactivator of CREB, functions both as a platform for recruiting other components of the transcriptional machinery and as a histone acetyltransferase (HAT) that alters chromatin structure.We previously showed that the transcriptional activity of cAMP-responsive element binding protein (CREB) plays a crucial role in neuronal plasticity in the pond snail Lymnaea stagnalis. However, there is no information on the molecular structure and HAT activity of CBP in the Lymnaea central nervous system (CNS), hindering an investigation of its postulated role in long-term memory (LTM). Here, we characterize the Lymnaea CBP (LymCBP) gene and identify a conserved domain of LymCBP as a functional HAT. Like CBPs of other species, LymCBP possesses functional domains, such as the KIX domain, which is essential for interaction with CREB and was shown to regulate LTM. In-situ hybridization showed that the staining patterns of LymCBP mRNA in CNS are very similar to those of Lymnaea CREB1. A particularly strong LymCBP mRNA signal was observed in the cerebral giant cell (CGC), an identified extrinsic modulatory interneuron of the feeding circuit, the key to both appetitive and aversive LTM for taste. Biochemical experiments using the recombinant protein of the LymCBP
In eukaryotes, CREB-binding protein (CBP), a coactivator of CREB, functions both as a platform for recruiting other components of the transcriptional machinery and as a histone acetyltransferase (HAT) that alters chromatin structure. We previously showed that the transcriptional activity of cAMP-responsive element binding protein (CREB) plays a crucial role in neuronal plasticity in the pond snail Lymnaea stagnalis. However, there is no information on the role how CBP plays in CREB-initiated plastic changes in Lymnaea. In this study, we characterized the Lymnaea CBP (LymCBP) gene and investigated the roles it plays in synaptic plasticity involved in regulating feeding behaviors. Similar to CBPs of other species, LymCBP possesses functional domains, such as KIX domain, which is essential for interaction with CREB and was shown to regulate long-term memory (LTM). In situ hybridization showed that the staining patterns of LymCBP mRNA in the central nervous system were very similar to those of Lymnaea CREB1 (LymCREB1). A particularly strong LymCBP mRNA signal was observed in the Cerebral Giant Cell (CGC), an identified extrinsic modulatory interneuron of the feeding circuit, key to both appetitive and aversive LTM for taste. Biochemical experiments using the recombinant protein of LymCBP HAT domain showed that its enzymatic activity was blocked by classical HAT inhibitors; i.e. curcumin, anacardic acid and garcinol. Preincubation of Lymnaea CNSs with these HAT inhibitors blocked cAMP-induced long-term potentiation between the CGC and the follower B1 motoneuron. We therefore suggest that HAT activity of LymCBP in the CGCs is a key factor in synaptic plasticity contributing to LTM after classical conditioning.
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