Either there's some problem with Protein E, or there's some new biology there. In the work it's found to interact with DNA-related proteins. In Fig 4D some similarity to histones is proposed, but the Protein E sequence compared (there in the figure to H2A) is incorrect. OK yes even with the correct sequence there is some similarity, but it looks quite low and limited just to half of what the authors propose. The match could just be casual because this is a putative transmembrane segment (Protein E is probably membrane bound) and the corresponding element in the H2A sequence is quite hydrophobic.