Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
Herpes simplex virus type 1 (HSV-1) protein ICP27 is a multifunctional regulator of gene expression that assumes different roles during the course of infection. Early in infection, ICP27 mediates the inhibition of cellular splicing, whereas, later it helps to recruit cellular RNA polymerase II (RNAP II) to viral replication sites and to facilitate viral RNA export. ICP27 has also been shown to stimulate translation of viral transcripts. ICP27 performs its activities by interacting with RNA and with an assortment of proteins. ICP27 binds viral RNAs in its role as an export adaptor. An ever increasing number of cellular proteins have been shown to interact with ICP27, including splicing factors, export proteins and RNAP II. A number of protein motifs within ICP27 have been predicted based upon sequence comparisons; however, detailed structural information is not yet available. Although much has been learned about the mechanisms by which ICP27 performs its roles, relatively little is known about how its activities are regulated. The roles and activities of ICP27 are the subject of this review.