Structure and expression of a cDNA encoding a histone H2A from Euglena gracilis

Abstract

Screening of a lambda gt11 cDNA expression library of Euglena gracilis with antibodies directed against histones H2 from maize resulted in the isolation of a full-length cDNA for a histone H2A. The open-reading frame of 408 bp corresponded to a protein of 136 amino acid residues (14 kDa). Despite the presence of a poly(A) tail, which is typical of plant histone mRNA but not of animal histone mRNA, the size of the deduced protein and its percentage of homology were closer to animal histone H2As than to plant or lower eukaryotic histone H2A. Sequence alignment revealed that the Euglena H2A protein was characterized by a shorter C-terminus and a N-terminus which extended 10 residues past the animal H2A. In contrast to other organisms studied, the expression of the Euglena H2A gene appeared to be almost constant during an entire life-cycle and presented no cell-stage-specific expression during development. Similar results are obtained for another histone gene, H3, and for beta-tubulin. Regulation of gene expression at a post-transcriptional level seems to be a general feature of Euglena.

Euglenoid flagellates: A multifaceted biotechnology platform

“…Most studied model eukaryotes including various mammalian species, land plants and yeast regulate gene expression predominantly at the transcriptional level. Most of the studies of gene expression in E. gracilis support the idea that nuclear gene expression is regulated at the posttranscriptional rather than at the transcriptional level (Hoffmeister et al, 2004;Keller et al, 1991;Kishore and Schwartzbach, 1992a,b;Levasseur et al, 1994;Madhusudhan et al, 2003;Saint-Guily et al, 1994;Vacula et al, 2001;Vesteg et al, 2009).…”

Unlocking the biological potential ofEuglena gracilis: evolution, cell biology and significance to parasitism

“…Rather unexpectedly, there is little evidence for transcriptional control, which is highly similar to kinetoplastids. Significant reliance on post-transcriptional processes has been long recognized as a feature of Euglena (Saint-Guily et al, 1994), but there is also mounting evidence that post-transcriptional, translational and degradation regulation are crucial determinants of protein abundance (Vogel and Marcotte, 2012).…”

Comparative molecular cell biology of phototrophic euglenids and parasitic trypanosomatids sheds light on the ancestor of Euglenozoa

“…Numerous studies have found that light and organic carbon availability are the primary regulators of E. gracilis nuclear and chloroplast gene expression (Schwartzbach, 1990(Schwartzbach, , 2017. The levels of histone H2A and H3 mRNAs vary throughout the cell cycle in animals and plants, but in E. gracilis they do not change (Saint-Guily, Schantz & Schantz, 1994). The levels of α-and β-tubulin mRNAs increase after deflagellation in Chlamydomonas spp.…”