Claveria-Gimeno, R. | bioRxiv Science

bioRxiv2020

Tyrosinase from mushroom Agaricus bisporus as an inhibitor of the Hepatitis C virus

Tyrosinases from both a commercial semi-purified Agaricus bisporus protein extract and directly isolated from white mushroom have been demonstrated to show antiviral activity against the Hepatitis C virus for the first time. The well-known tyrosinase from A. bisporus (TyrAB) of 45kDa and a newly discovered 50-kDa isoform from this tyrosinase (Tyr50kDa) have been tested. Cell toxicity and antiviral activity of tyrosinases in cultured Huh 5-2 liver tumor cells transfected with a replicon system (a plasmid that includes all non-structural Hepatitis C virus proteins and replicates autonomously) was determined. Native TyrAB was able to inhibit the replication of the hepatitis C virus without inducing toxicity in liver cells. In addition, the post-translational isoform of Tyr50kDa showed higher antiviral capacity than the former (up to 10 times greater), also exhibiting 10 times higher activity than the commercial drug Ribavirin(R). This antiviral activity was directly proportional to the enzymatic activity of tyrosinases, since no antiviral capacity was observed for the inactive enzymes. The tyrosinases approach could represent a new antiviral inhibition mechanism, through a catalytic mechanism of selective hydroxylation of key role tyrosine residues in viral proteases. The tyrosinases directly extracted from fresh mushrooms (containing both tyrosinases) showed similar antiviral activity and, therefore, might provide low-cost drugs for the treatment of hepatitis C.

microbiology↗

bioRxiv2018

MeCP2-E1 isoform is a dynamically expressed, weakly DNA-bound protein with different protein and DNA interactions compared to MeCP2-E2

MeCP2 - a chromatin-binding protein associated with Rett syndrome - has two main isoforms, MeCP2-E1 and MeCP2-E2, with 96% amino acid identity differing in a few N-terminal amino acid residues. Previous studies have shown brain region-specific expression of these isoforms which, in addition to their different cellular localization and differential expression during brain development, suggest they may also have non-overlapping molecular mechanisms. However, differential functions of MeCP2-E1 and E2 remain largely unexplored. Here, we show that the N-terminal domains (NTD) of MeCP2-E1 and E2 modulate the ability of the methyl binding domain (MBD) to interact with DNA as well as influencing the turnover rates, binding dynamics, response to nuclear depolarization, and circadian oscillations of the two isoforms. Our proteomics data indicate that both isoforms exhibit unique interacting protein partners. Moreover, genome-wide analysis using ChIP-seq provide evidence for a shared as well as a specific regulation of different sets of genes. Our findings provide insight into the functional complexity of MeCP2 by dissecting differential aspects of its two isoforms.\n\nSignificanceWhether the two E1 and E2 isoforms of MeCP2 have different structural and/or functional implications has been highly controversial and is not well known. Here we show that the relatively short N-terminal sequence variation between the two isoforms impinges them with an important DNA binding difference. Moreover, MeCP2-E1 and E2 exhibit a different cellular dynamic behavior and have some distinctive interacting partners. In addition, while sharing genome occupancy they specifically bind to several distinctive genes.

biochemistry↗