The functions of Mud2 and Prp19C components in transcription and TREX occupancy

Different steps in gene expression from transcription to mRNA processing and nuclear mRNP export are connected intimately for quality control. The TREX complex is a key player that couples transcription elongation to nuclear mRNA export (Strasser, Masuda et al. 2002). The Prp19 complex (Prp19C, also known as NTC complex), originally known for its role in splicing, plays a role in stabilizing TREX complex at transcribed genes. Prp19C interacts with the TREX in vivo and is also required for efficient transcription (Chanarat, Seizl et al. 2011). Furthermore, it has been reported in the mammalian cells that Prp19C is recruited to transcriptional machinery by the early splicing factor U2AF65 (David, Boyne et al. 2011). U2AF65 interacts directly with Prp19C and the phosphorylated CTD, leading to an increased recruitment of both U2AF65 and Prp19C in a CTD-dependent manner, which enhances the splicing reaction. In Saccharomyces cerevisiae, Mud2 is the potential homologue of U2AF65. In this study, a novel function of Mud2 in the gene expression, namely in transcription, was identified. Using chromatin immunoprecipitation (ChIP), it was shown that Mud2 is recruited to both intron‐containing and intronless genes in a transcription-dependent manner. Mud2 binds directly to the S2-phosphorylated CTD and S2 phosphorylation is needed for its full occupancy at transcribed genes. Furthermore, Mud2 coimmunoprecipitates Prp19C in vivo in an RNA-independent manner and is also required for maintaining Prp19C and TREX occupancy at transcribed genes. Using in vivo and in vitro transcription assays, it was shown that Mud2 is necessary for full transcriptional activity by RNA Polymerase II (RNAPII). Taken together, Mud2 can be classified as a novel transcription factor that is necessary for the recruitment of mRNA-binding proteins to transcribed genes. In addition, a direct interaction between the Prp19C and THO, a sub-complex of TREX, was shown. Prp19C consists of the essential subunits Prp19, Cef1, Clf1, Syf1, Cwc2 and Prp46 and the non-essential subunits Ntc20, Snt309, Isy1 and Syf2. However, the molecular mechanism of Prp19C function and the roles of its individual subunits in maintaining TREX at transcribed genes and in transcription have remained unknown. In this study, the three non-essential subunits of Prp19C, Isy1, Ntc20 and Syf2, were investigated for their roles in Prp19C-TREX interaction and transcription. Additionally, an NTC related protein (NTR), which is a component of a complex containing Cef1 and hence named Cwc15 (complexed with Cef1), was also analyzed. The functions of these four proteins in Prp19C and TREX occupancy as well as Prp19C-TREX, Prp19C-Mud2 and Prp19C-RNAPII interaction were determined. Taken together, this analysis shows that specific Prp19C subunits play differential roles in gene expression

Mud2 functions in transcription by recruiting the Prp19 and TREX complexes to transcribed genes

The different steps of gene expression are intimately linked to coordinate and regulate this complex process. During transcription, numerous RNA-binding proteins are already loaded onto the nascent mRNA and package the mRNA into a messenger ribonucleoprotein particle (mRNP). These RNA-binding proteins are often also involved in other steps of gene expression than mRNA packaging. For example, TREX functions in transcription, mRNP packaging and nuclear mRNA export. Previously, we showed that the Prp19 splicing complex (Prp19C) is needed for efficient transcription as well as TREX occupancy at transcribed genes. Here, we show that the splicing factor Mud2 interacts with Prp19C and is needed for Prp19C occupancy at transcribed genes in Saccharomyces cerevisiae. Interestingly, Mud2 is not only recruited to intron-containing but also to intronless genes indicating a role in transcription. Indeed, we show for the first time that Mud2 functions in transcription. Furthermore, these functions of Mud2 are likely evolutionarily conserved as Mud2 is also recruited to an intronless gene and interacts with Prp19C in Drosophila melanogaster. Taken together, we classify Mud2 as a novel transcription factor that is necessary for the recruitment of mRNA-binding proteins to the transcription machinery. Thus, Mud2 is a multifunctional protein important for transcription, splicing and most likely also mRNP packaging

Polarographic & Cyclic Voltammetric Investigations on p-[(8-Hydroxyquinolyl)azo] benzenesulphonamides

650-65

Role of the pangolin in origin of SARS-CoV-2: an evolutionary perspective

After the recent emergence of SARS-CoV-2 infection, unanswered questions remain related to its evolutionary history, path of transmission or divergence and role of recombination. There is emerging evidence on amino acid substitutions occurring in key residues of the receptor-binding domain of the spike glycoprotein in coronavirus isolates from bat and pangolins. In this article, we summarize our current knowledge on the origin of SARS-CoV-2. We also analyze the host ACE2-interacting residues of the receptor-binding domain of spike glycoprotein in SARS-CoV-2 isolates from bats, and compare it to pangolin SARS-CoV-2 isolates collected from Guangdong province (GD Pangolin-CoV) and Guangxi autonomous regions (GX Pangolin-CoV) of South China. Based on our comparative analysis, we support the view that the Guangdong Pangolins are the intermediate hosts that adapted the SARS-CoV-2 and represented a significant evolutionary link in the path of transmission of SARS-CoV-2 virus. We also discuss the role of intermediate hosts in the origin of Omicron

Alveolar regeneration in COVID-19 patients: a network perspective

A viral infection involves entry and replication of viral nucleic acid in a host organism, subsequently leading to biochemical and structural alterations in the host cell. In the case of SARS-CoV-2 viral infection, over-activation of the host immune system may lead to lung damage. Albeit the regeneration and fibrotic repair processes being the two protective host responses, prolonged injury may lead to excessive fibrosis, a pathological state that can result in lung collapse. In this review, we discuss regeneration and fibrosis processes in response to SARS-CoV-2 and provide our viewpoint on the triggering of alveolar regeneration in coronavirus disease 2019 (COVID-19) patients

Genome-wide scan for potential CD4+ T-cell vaccine candidates in Candida auris by exploiting reverse vaccinology and evolutionary information

Candida auris is a globally emerging fungal pathogen responsible for causing nosocomial outbreaks in healthcare associated settings. It is known to cause infection in all age groups and exhibits multi-drug resistance with high potential for horizontal transmission. Because of this reason combined with limited therapeutic choices available, C. auris infection has been acknowledged as a potential risk for causing a future pandemic, and thus seeking a promising strategy for its treatment is imperative. Here, we combined evolutionary information with reverse vaccinology approach to identify novel epitopes for vaccine design that could elicit CD4+ T-cell responses against C. auris. To this end, we extensively scanned the family of proteins encoded by C. auris genome. In addition, a pathogen may acquire substitutions in epitopes over a period of time which could cause its escape from the immune response thus rendering the vaccine ineffective. To lower this possibility in our design, we eliminated all rapidly evolving genes of C. auris with positive selection. We further employed highly conserved regions of multiple C. auris strains and identified two immunogenic and antigenic T-cell epitopes that could generate the most effective immune response against C. auris. The antigenicity scores of our predicted vaccine candidates were calculated as 0.85 and 1.88 where 0.5 is the threshold for prediction of fungal antigenic sequences. Based on our results, we conclude that our vaccine candidates have the potential to be successfully employed for the treatment of C. auris infection. However, in vivo experiments are imperative to further demonstrate the efficacy of our design