YjgA plays dual roles in enhancing PTC maturation.

Ribosome biogenesis is a highly regulated cellular process that involves the control of numerous assembly factors. The small protein YjgA has been reported to play a role in the late stages of 50S assembly. However, the precise molecular mechanism underlying its function remains unclear. In this study, cryo-electron microscopy (cryo-EM) structures revealed that depletion of YjgA or its N-terminal loop in Escherichia coli both lead to the accumulation of immature 50S particles with structural abnormalities mainly in peptidyl transferase center (PTC) and H68/69 region. CryoDRGN analysis uncovered 8 and 6 distinct conformations of pre50S for ΔyjgA and YjgA-ΔNloop, respectively. These conformations highlighted the role of the N-terminal loop of YjgA in integrating uL16 and stabilizing H89 in PTC, which was further verified by the pull-down assays of YjgA and its mutants with uL16. Together with the function of undocking H68 through the binding of its C-terminal CTLH-like domain to the base of the L1 stalk, YjgA facilitates the maturation of PTC. This study identified critical domains of YjgA contributing to 50S assembly efficiency, providing a comprehensive understanding of the dual roles of YjgA in accelerating ribosome biogenesis and expanding our knowledge of the intricate processes governing cellular protein synthesis.

Implication of Stm1 in the protection of eIF5A, eEF2 and tRNA through dormant ribosomes.

Background: Dormant ribosomes are typically associated with preservation factors to protect themselves from degradation under stress conditions. Stm1/SERBP1 is one such protein that anchors the 40S and 60S subunits together. Several proteins and tRNAs bind to this complex as well, yet the molecular mechanisms remain unclear. Methods: Here, we reported the cryo-EM structures of five newly identified Stm1/SERBP1-bound ribosomes. Results: These structures highlighted that eIF5A, eEF2, and tRNA might bind to dormant ribosomes under stress to avoid their own degradation, thus facilitating protein synthesis upon the restoration of growth conditions. In addition, Ribo-seq data analysis reflected the upregulation of nutrient, metabolism, and external-stimulus-related pathways in the ∆stm1 strain, suggesting possible regulatory roles of Stm1. Discussion: The knowledge generated from the present work will facilitate in better understanding the molecular mechanism of dormant ribosomes.

Interaction with the Receptor SLAM and Baculovirus Surface Display of Peste des petits ruminants Virus Hemagglutinin.

Peste des petits ruminants (PPR) is an acute, highly infectious, and highly pathogenic disease, which mainly damages small ruminants such as goats and sheep. Hemagglutinin protein (H), the main antigenic protein of peste des petits ruminants virus (PPRV), has been a hot spot in the research of genetic engineering vaccine for PPRV. In this study, the silkworm baculovirus surface display technology is combined with the transmembrane structure of the silkworm baculovirus envelope protein GP64 and different characteristics of the promoters to display four kinds of fusion proteins, which contain Pph-H, Pph-HJ, Pie1-H, and Pie1-HJ. The fusion proteins displayed on baculovirus surface have been detected by western blotting, cell surface immunofluorescence, and immunogold electron microscopy. In addition, the dominant form of PPR H displayed on baculovirus surface has been determined which is fusion protein mediated by Pph containing the hemagglutinin protein and full-length GP64, Pph-H. Furthermore, by comparing the fluorescence intensity of binding of hemagglutinin protein and signaling lymphocyte activation molecules (SLAM) in Vero-SLAM cells by immunocytochemistry, Pph-H can be combined with the receptor protein of PPRV, SLAM. It provides technical support for displaying the different structure of hemagglutinin and exploring the key sites of hemagglutinin and SLAM binding. Meanwhile, it is important for exploring the pathogenesis and immune mechanism of PPRV.

IFN-γ establishes interferon-stimulated gene-mediated antiviral state against Newcastle disease virus in chicken fibroblasts.

Newcastle disease virus (NDV) causes severe economic losses through severe morbidity and mortality and poses a significant threat to the global poultry industry. Significant efforts have been made to develop novel vaccines and therapeutics; however, the interaction of NDV with the host is not yet fully understood. Interferons (IFNs), an integral component of innate immune signaling, act as the first line of defense against invading viruses. Compared with the mammalian repertoire of IFNs, limited information is available on the antiviral potential of IFNs in chickens. Here, we expressed chicken IFN-γ (chIFN-γ) using a baculovirus expression vector system, characterized its antiviral potential against NDV, and determined its antiviral potential. Priming of chicken embryo fibroblasts with chIFN-γ elicited an antiviral environment in primary cells, which was mainly due to interferon-stimulated genes (ISGs). A genome-wide transcriptomics approach was used to elucidate the possible signaling pathways associated with IFN-γ-induced immune responses. RNA-sequencing (RNA-seq) data revealed significant induction of ISG-associated pathways, activated temporal expression of ISGs, antiviral mediators, and transcriptional regulators in a cascade of antiviral responses. Collectively, we found that IFN-γ significantly elicited an antiviral response against NDV infection. These data provide a foundation for chIFN-γ-mediated antiviral responses and underpin functional annotation of these important chIFN-γ-induced antiviral influencers.