Biology subjects

Harrington, E. M.

Publications and source records attributed to Harrington, E. M..

3 recordsLinked to original sources

bioRxiv2024

EMG1 methyltransferase activity regulates ribosome occupancy at viral uORFs

Viruses do not encode their own translational machinery and rely exclusively on the translational machinery of the host cell for the synthesis of viral proteins. Viruses have evolved diverse mechanisms to redirect the cellular translation apparatus to favour viral transcripts. A unique mechanism employed by Kaposis sarcoma-associated herpesvirus (KSHV) involves manipulation of cellular ribosome composition, producing virus-induced specialised ribosomes. These ribosomes scan through KSHV uORFs in late lytic genes, allowing efficient translation of downstream main KSHV ORFs. Herein, we highlight the enhanced association of the ribosomal biogenesis factor EMG1 with precursor-40S ribosome complexes during KSHV lytic replication. Depletion of EMG1 results in significantly reduced expression of viral proteins and progression through the lytic cascade, culminating in a dramatic reduction of infectious virus production. We further demonstrate that the methyltransferase activity of EMG1 is required for effective regulation of translation of KSHV uORFs in late lytic genes.

microbiology↗

bioRxiv2024

Virus-induced paraspeckle-like condensates are essential hubs for gene expression and their formation drives genomic instability

The nucleus is a highly structured environment containing multiple membrane-less bodies formed through liquid-liquid phase separation. These provide spatial separation and concentration of specific biomolecules enabling efficient and discrete processes to occur which regulate gene expression. One such nuclear body, paraspeckles, are comprised of multiple paraspeckle proteins (PSPs) built around the architectural RNA, NEAT1_2. Paraspeckle function is yet to be fully elucidated but has been implicated in a variety of developmental and disease scenarios. We demonstrate that Kaposis sarcoma-associated herpesvirus (KSHV) drives formation of structurally distinct paraspeckles with a dramatically increased size and altered protein composition that are essential for productive lytic replication. We highlight these virus-induced paraspeckle-like structures form adjacent to virus replication centres, functioning as RNA processing hubs for both viral and cellular transcripts during infection. Notably, we reveal that PSP sequestration into virus-induced paraspeckle-like structures results in increased genome instability during both KSHV and Epstein Barr virus (EBV) infection, implicating their formation in virus-mediated tumorigenesis.

microbiology↗

bioRxiv2021

Chemoproteomics Enabled Discovery of Selective Probes for NuA4 Factor BRD8

Bromodomain-containing proteins frequently reside in multisubunit chromatin complexes with tissue or cell state-specific compositions. Recent studies have revealed tumor-specific dependencies on the BAF complex bromodomain subunit BRD9 that are a result of recurrent mutations afflicting the structure and composition of associated complex members. To enable the study of ligand engaged complex assemblies, we established a chemoproteomics approach using a functionalized derivative of the BRD9 ligand BI-9564 as an affinity matrix. Unexpectedly, in addition to known interactions with BRD9 and associated BAF complex proteins, we identify a previously unreported interaction with members of the NuA4 complex through the bromodomain-containing subunit BRD8. We apply this finding, alongside homology model guided design, to develop chemical biology approaches for the study of BRD8 inhibition, and to arrive at first-in-class selective and cellularly active probes for BRD8. These tools will empower further pharmacological studies of BRD9 and BRD8 within respective BAF and NuA4 complexes.

biochemistry↗