Dinoflagellate viral nucleoproteins

Abstract

Dinoflagellates are an exceptional group of unicellular microorganisms that exhibit a novel perspective in chromatin biology as they bear a number of unique characteristics. Their genome sizes are the largest among eukaryotes. Despite this, the conventional nucleosomal organization in eukaryotic chromosomes are not detectable in the nucleus of dinoflagellates. A group of dinoflagellates Histone-Like Proteins (HLPs) are the major nuclear basic proteins. They were proposed to be the candidate for regulating gene expression and maintaining the extra-chromosomal loops due to their abundance and localization. Another significant group of basic nuclear proteins, the Dinoflagellate Viral Nucleoproteins (DVNPs), were recently suggested to be related to the genome expansion and loss of nucleosomes during the course of dinoflagellates evolution. The biological functions of this group of protein have yet to be revealed. The CcDVNP1 gene was cloned in Crypthecodinium cohnii. This CcDVNP1 from C. cohnii was shown to exhibit similar molecular properties of those DVNPs from other dinoflagellates. The transcript and expression level of CcDVNP1 were shown to peak at G2/M phase during the cell cycle, which followed a similar expression pattern to that of HCc3. DNA-damage could induce the up-regulation of CcDVNP1, whereas incubation under high temperature posed no effects on the expression of CcDVNP1. On the other hand, osmolarity stress could significantly reduce the transcript level of CcDVNP1. Inhibiting the three classes of RNA polymerases surprisingly increased the protein expression level of CcDVNP1. Integrating all the experimental data, I proposed that DVNP is involved in the regulation of transcriptional activities.

Date of Award	2014
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology