The use of BirA-BAP system to study the effect of US2 and US11 on MHC class I heavy chain in cells

Insights into the Transcriptome of Human Cytomegalovirus: A Comprehensive Review

Human cytomegalovirus (HCMV) is a widespread pathogen that poses significant risks to immunocompromised individuals. Its genome spans over 230 kbp and potentially encodes over 200 open-reading frames. The HCMV transcriptome consists of various types of RNAs, including messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), with emerging insights into their biological functions. HCMV mRNAs are involved in crucial viral processes, such as viral replication, transcription, and translation regulation, as well as immune modulation and other effects on host cells. Additionally, four lncRNAs (RNA1.2, RNA2.7, RNA4.9, and RNA5.0) have been identified in HCMV, which play important roles in lytic replication like bypassing acute antiviral responses, promoting cell movement and viral spread, and maintaining HCMV latency. CircRNAs have gained attention for their important and diverse biological functions, including association with different diseases, acting as microRNA sponges, regulating parental gene expression, and serving as translation templates. Remarkably, HCMV encodes miRNAs which play critical roles in silencing human genes and other functions. This review gives an overview of human cytomegalovirus and current research on the HCMV transcriptome during lytic and latent infection.

Application of the biotin-labeled toxin mutant for affinity isolation of associated proteins in the mammalian cells

Cholera toxin (CT), one of the AB₅ bacterial toxin families, is produced by Vibrio cholerae, breeches the intestinal epithelial barrier and enters host epithelial cells to cause the massive secretory diarrhea. This study focused on understanding the retro-translocation machinery of the bacterial toxin using biotin-avidin technology to explain toxin trafficking from the endoplasmic reticulum (ER) to the cytosol. Because the association between the A1 chain of CT and other components of the retro-translocation machinery is likely transient or very weak, the successful bioengineering of such a mutant to be trapped as an intermediate in ER is essential for affinity isolation and further analysis. Here, we prepared a mutant toxin that 15 amino acid Biotin Acceptor Peptide (BAP) was fused to the C-terminal of A1 chain of CT. Biotinylation efficiency of the BAP-inserted cholera toxin (BT) was nearly 100%. Moreover, BT was functionally toxic and successfully pulled down by NeutrAvidin in vitro and in vivo. However, NeutrAvidin-bound biotinylated BT was not toxic. These results suggest the possibility of a plug effect of the biotin-NeutrAvidin-BT complex stuck in the ER without retro-translocation to the cytosol. Therefore, this model might identify the interacting proteins with A1 chain of CT in the host cells by holding the moment of retro-translocation of the bacterial toxin. In conclusion, this study established the model using biotin-avidin technology to elucidate the molecular basis for retro-translocation of bacterial toxin from within the lumen of ER to the cytosol.