Abstract
The most important sources of new components of genomes are transposable elements, which can occupy more than half of the nucleotide sequence of the genome in higher eukaryotes. Among the mobile components of a genome, a special place is occupied by retroelements, which are similar to retroviruses in terms of their mechanisms of integration into a host genome. The process of positive selection of certain sequences of transposable elements and retroviruses in a host genome is commonly called molecular domestication. There are many examples of evolutionary adaptations of gag (retroviral capsid) sequences as new regulatory sequences of different genes in mammals, where domesticated gag genes take part in placenta functioning and embryogenesis, regulation of apoptosis, hematopoiesis, and metabolism. The only gag-related gene has been found in the Drosophila genome—Gagr. According to the large-scale transcriptomic and proteomic analysis data, the Gagr gene in D. melanogaster is a component of the protein complex involved in the stress response. In this work, we consider the evolutionary processes that led to the formation of a new function of the domesticated gag gene and its adaptation to participation in the stress response. We discuss the possible functional role of the Gagr as part of the complex with its partners in Drosophila, and the pathway of evolution of proteins of the complex in eukaryotes to determine the benefit of the domesticated retroelement gag gene.
Highlights
The term “molecular domestication” was first proposed by Wolfgang Miller in 1997 to describe the phenomenon of the adaptation of the sequences of mobile elements by the organism for its benefit [1]
Several gene families with a retroviral gag origin (PNMA, Mart, and SIRH) have been found, which play an important role in placenta functioning and embryogenesis, regulation of apoptosis, hematopoiesis, metabolism, etc. [2–6]
A number of other domesticated retroelement gag genes may be involved in protection against retroviruses [7–9]
Summary
The term “molecular domestication” was first proposed by Wolfgang Miller in 1997 to describe the phenomenon of the adaptation of the sequences of mobile elements by the organism for its benefit [1]. We discuss the possible functional role of the Gagr as part of the complex with its partners in Drosophila, and the pathway of evolution of proteins of the complex in eukaryotes to determine the benefit of the domesticated retroelement gag gene. The PDI gene family contains 21 members, varying in domain composition, molecular weight, tissue expression, and cellular processing; loss of Pdi activity has been associated with pathogenesis, most commonly related to the unfolded protein response (UPR) [32]. Pdi is induced during ER stress and serves as a cellular defense against protein misfolding via its chaperone activity [39]. It is responsible for the isomerization, formation, and rearrangement of protein disulfide bonds, thereby providing another mechanism by which native protein conformation is maintained [40]. The presence of eIF3j is important both for maintaining the stability of the entire complex and for its key conformational rearrangements [50]
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