HHV Capsid Portal Protein, or HSV-1 UL-6 protein, is the protein which forms a cylindrical portal in the capsid of Herpes simplex virus (HSV-1). The protein is commonly referred to as the HSV-1 UL-6 protein because it is the transcription product of Herpes gene UL-6.
The Herpes viral DNA enters and exits the capsid via the capsid portal. The capsid portal is formed by twelve copies of portal protein arranged as a ring; the proteins contain a leucine zipper sequence of amino acids which allow them to adhere to each other. Each icosahedral capsid contains a single portal, located in one vertex.
The portal is formed during initial capsid assembly and interacts with scaffolding proteins that construct the procapsid. When the capsid is nearly complete, the viral DNA enters the capsid (i.e., the DNA is encapsidated) by a mechanism involving the portal and a DNA-binding protein complex similar to bacteriophage terminase. Multiple studies suggest an evolutionary relationship between Capsid Portal Protein and bacteriophage portal proteins.
When virus infects a cell, it is necessary for the viral DNA to be released from the capsid. The Herpes virus DNA exits through the capsid portal.
The genetic sequence of HSV-1 gene UL-6 is conserved across the Herpesviridae family and this family of genes is known as the "Herpesvirus UL6-like" gene family. "UL-6" is nomenclature meaning that the protein is genetically encoded by the sixth (6th) open reading frame found in the viral genome segment named "Unique-Long (UL)".
Read more about HHV Capsid Portal Protein: Studies
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