Bacterial SET domain proteins and their role in eukaryotic chromatin modification

Abstract

It has been shown by many researchers that SET-domain containing proteins modify chromatin structure and, as expected, genes coding for SET-domain containing proteins have been found in all eukaryotic genomes sequenced to date. However, during the last years, a great number of bacterial genomes have been sequenced and an important number of putative genes involved in histone post-translational modifications (histone PTMs) have been identified in many bacterial genomes. Here, I aim at presenting an overview of SET domain genes that have been identified in numbers of bacterial genomes based on similarity to SET domains of eukaryotic histone methyltransferases. I will argue in favor of the hypothesis that SET domain genes found in extant bacteria are of bacterial origin. Then, I will focus on the available information on pathogen and symbiont SET-domain containing proteins and their targets in eukaryotic organisms, and how such histone methyltransferases allow a pathogen to inhibit transcriptional activation of host defense genes.

Keywords: SET-domain; bacteria; epigenetics; histone methyltransferases; pathogen; symbiont.

Figure 1

Control of host gene expression by bacterial SET domain proteins and their mode of action. Schematic representation of Burkholderia, Legionella, Chlamydia, and Bacillus secreted factors involved in the control of gene expression of host cells, as detailed in the text. Me: histone methylation; H3K14me3: tri-methylated lysine 14 of histone H3; H3K4me2: di-methylated lysine 4 of histone H3; H3K9me3: tri-methylated lysine 9 of histone H3; H1K: histone H1 lysine.