The polytene chromosomes of Drosophila melanogaster consist of condensed heterochromatin regions most of which are in the chromocenter, telomeres, and the fourth chromosome. Whereas suppressor of variegation 3-9 [SU(VAR)3-9], a histone methyltransferase, is mainly responsible for lysine 9 of histone H3 (H3K9) methylation of the chromocenter and consequent binding of the heterochromatin-protein HP1, the enzyme for painting of the fourth chromosome by H3K9 methylation has been elusive. We show here that dSETDB1, the Drosophila ortholog of the mammalian SETDB1, is an authentic H3K9 methyltransferase and a pleio-
Hepatitis D virus (HDV) encodes two proteins, the 24-kDa small delta antigen (S-HDAg) and 27-kDa large delta antigen (L-HDAg) in its single open reading frame. Both of them had been identified as nuclear phosphoproteins. Moreover, the phosphorylated form of S-HDAg was shown to be important for HDV replication. However, the kinase responsible for S-HDAg phosphorylation remains unknown. Therefore, we employed an ingel kinase assay to search candidate kinases and indeed identified a kinase with a molecular mass of about 68 kDa. Much evidence demonstrated this kinase to be the double-stranded RNA-activated kinase, PKR. The immunoprecipitated endogenous PKR was sufficient to catalyze S-HDAg phosphorylation, and the kinase activity disappeared in the PKR-depleted cell lysate. The S-HDAg and PKR could be co-immunoprecipitated together, and both of them co-located in the nucleolus. The LC/MS/MS analysis revealed that the serine 177, serine 180, and threonine 182 of S-HDAg were phosphorylated by PKR in vitro. This result was consistent with previous phosphoamino acid analysis indicating that serine and threonine were phosphorylation targets in S-HDAg. Furthermore, serine 177 was also shown to be the predominant phosphorylation site for S-HDAg purified the from cell line. In dominant negative PKR-transfected cells, the level of phosphorylated S-HDAg was suppressed, but replication of HDV was enhanced. Other than human immunodeficiency virus type 1 trans-activating protein (Tat), S-HDAg is another viral protein phosphorylated by PKR that may regulates HDV replication and viral response to interferon therapy.Hepatitis delta virus (HDV) 1 is the satellite virus of hepatitis B virus (1, 2), since it requires the hepatitis B virus envelope surface antigen (HBsAg) for viral particle assembly (3-5). Upon superinfection or co-infection with hepatitis B virus, HDV may cause fulminant hepatitis and progressive chronic liver disease (6, 7). The genome of HDV is a circular, single-stranded RNA that resembles the structure of plant viroid (8, 9). HDV contains the ribozyme domains for self-cleavage and self-ligation in both genomic and antigenomic strands of RNA (10, 11). Similar to viroid replication, HDV undergoes a double rolling circle scheme. However, different from viroids, HDV encodes two proteins translated from the same mRNA, small delta antigen (S-HDAg) and large delta antigen (L-HDAg) (12, 13). This viral mRNA is responsible for S-HDAg production. LHDAg is translated from the same open reading frame through a specific RNA editing process by which the UAG amber termination codon of S-HDAg was converted to UGG tryptophan codon and an additional 19 amino acids were made (14,15). This adenosine-to-inosine RNA editing is catalyzed by doublestranded RNA adenosine deaminase (15, 16). Although both forms of delta antigens (HDAg) share an identical N-terminal 194 amino acids, their functions are quite different. The SHDAg is essential for viral replication, whereas L-HDAg inhibits replication and is required for viral assembly (17-19...
For many, “DNA mimic protein” (DMP) remains an unfamiliar term. The key feature of these proteins is their DNA‐like shape and charge distribution, and they affect the activity of DNA‐binding proteins by occupying their DNA‐binding domains. Functionally, DMPs regulate mechanisms such as gene expression, restriction, and DNA repair as well as the nucleosome package. Although a few DMPs, such as phage uracil DNA glycosylase inhibitor (UGI) and overcome classical restriction (Ocr), were reported about 20 years ago, only a small number of DMPs have been studied to date. In 2014, we reviewed the functional and structural features of 16 DMPs that were known at the time. Now, seven new DMPs, namely anti‐CRISPR suppressors AcrF2, AcrF10 and AcrIIA4, human immunodeficiency virus essential factor VPR, multi‐functional inhibitor anti‐restriction nuclease (Arn), translational regulator AbbA, and putative Z‐DNA mimic MBD3, have been reported. In addition, further study of two previously known DMPs, DMP19 and SAUGI, increased our knowledge of their importance and function. Here, we discuss these updated results and address how several characteristics of the structure/sequence of DMPs (e.g. the DNA‐like charge distribution and structural D/E‐rich repeats) might someday be used to identify new DMPs using bioinformatic approach. © 2018 IUBMB Life, 71(5):539–548, 2019
There has been a recent increase in the development of delivery systems based on red blood cells (RBCs) for light-mediated imaging and therapeutic applications. These constructs are able to take advantage of the immune evasion properties of the RBC, while the addition of an optical cargo allows the particles to be activated by light for a number of promising applications. Here, we review some of the common fabrication methods to engineer these constructs. We also present some of the current light-based applications with potential for clinical translation, and offer some insight into future directions in this exciting field.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.