Influence of the P6 effector protein of Cauliflower mosaic virus (CaMV) on the sustained expression and subcellular localization of the CaMV movement protein.

The P6 protein of cauliflower mosaic virus (CaMV) is a multifunctional protein that forms the electron dense, amorphous inclusion bodies that accumulate in the cytoplasm and has been shown to physically interact with all other CaMV proteins, including the CaMV movement protein (P1). In this study, we have investigated the subcellular localization of the P6 and P1 proteins in transient expression assays in Nicotiana benthamiana, as well as the influence of P6 on the expression and subcellular localization of P1. A version of P6 tagged with RFP was shown to envelop the endoplasmic reticulum (ER), whereas P1 tagged with RFP was shown to induce the fragmentation of the ER.

Transient expression of cauliflower mosaic virus (CaMV) P6-GFP complements a defective CaMV replicon to facilitate viral gene expression, replication and virion formation.

Over the past decades, several studies have examined the subcellular localization of the cauliflower mosaic virus (CaMV) P6 protein by tagging it with GFP (P6-GFP). These investigations have been essential in the development of models for inclusion body formation, nuclear transport, and microfilament-associated intracellular movement of P6 inclusion bodies for delivery of virions to plasmodesmata. Although it was shown early on that the translational transactivation function of P6-GFP was comparable to wild type P6, it has not been possible to incorporate a P6-GFP gene into an infectious clone of CaMV.

Functions of HP1 proteins in transcriptional regulation.

In eukaryotes, DNA is packaged into chromatin, which presents significant barriers to transcription. Non-histone chromatin proteins such as the Heterochromatin Protein 1 (HP1) proteins are critical regulators of transcription, contributing to gene regulation through a variety of molecular mechanisms. HP1 proteins are highly conserved, and many eukaryotic genomes contain multiple HP1 genes.

The Drosophila HP1 family is associated with active gene expression across chromatin contexts.

Drosophila Heterochromatin Protein 1a (HP1a) is essential for heterochromatin formation and is involved in transcriptional silencing. However, certain loci require HP1a to be transcribed. One model posits that HP1a acts as a transcriptional silencer within euchromatin while acting as an activator within heterochromatin.

Cauliflower mosaic virus P6 inclusion body formation: A dynamic and intricate process.

During an infection, Cauliflower mosaic virus (CaMV) forms inclusion bodies (IBs) mainly composed of viral protein P6, where viral activities occur. Because viral processes occur in IBs, understanding the mechanisms by which they are formed is crucial. FL-P6 expressed in N.