Browsing by Author "Sathanantham, Preethi"

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    Characterization of an Amphipathic Alpha-Helix in the Membrane Targeting and Viral Genome Replication of Brome Mosaic Virus
    Sathanantham, Preethi (Virginia Tech, 2022-03-01)
    Positive-strand RNA viruses associate with specific organelle membranes of host cells to establish viral replication complexes. The replication protein 1a of brome mosaic virus associates strongly with the nuclear endoplasmic reticulum (ER) membranes, invaginates membranes into the lumen, and recruits various host proteins to establish replication complexes termed spherules. 1a has a strong affinity towards the perinuclear ER membrane, however, the structural features in 1a that dictate its membrane associations and thereby membrane remodeling activities are unclear. This study examined the possible role of an amphipathic α-helix, helix B, in BMV 1a's membrane association. Deletion or single substitution of multiple amino acids of helix B abolished BMV 1a's localization to nuclear ER membranes. Additional reporter-based, gain-of-function assays showed that helix B is sufficient in targeting several soluble proteins to the nuclear ER membranes. Furthermore, we found that the helix B-mediated organelle targeting is a functionally conserved feature among positive-strand RNA viruses of the alphavirus-like superfamily that includes notable human viruses such as Hepatitis E virus and Rubella virus as well as plant viruses such as cucumber mosaic virus and cowpea chlorotic mottle virus. Our results demonstrate a critical role for helix B across members of the alphavirus-like superfamily in anchoring viral replication complexes to the organelle membranes. We anticipate our findings to be a starting point for the development of sophisticated models to use helix B as a novel target for the development of antivirals for positive-strand RNA viruses that belong to the alphavirus-like superfamily.
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    A conserved viral amphipathic helix governs the replication site-specific membrane association
    Sathanantham, Preethi; Zhao, Wenhao; He, Guijuan; Murray, Austin; Fenech, Emma; Diaz, Arturo; Schuldiner, Maya; Wang, Xiaofeng (PLOS, 2022-09-01)
    Positive-strand RNA viruses assemble their viral replication complexes (VRCs) on specific host organelle membranes, yet it is unclear how viral replication proteins recognize and what motifs or domains in viral replication proteins determine their destinations. We show here that an amphipathic helix, helix B in replication protein 1a of brome mosaic virus (BMV), is necessary for 1a s localization to the nuclear endoplasmic reticulum (ER) membrane where BMV assembles its VRCs. Helix B is also sufficient to target soluble proteins to the nuclear ER membrane in yeast and plant cells. We further show that an equivalent helix in several plant-and human-infecting viruses of the Alsuviricetes class targets fluorescent proteins to the organelle membranes where they form their VRCs, including ER, vacuole, and Golgi membranes. Our work reveals a conserved helix that governs the localization of VRCs among a group of viruses and points to a possible target for developing broad-spectrum antiviral strategies.