Bacterial contribution to genesis of the novel germ line determinantoskar

Abstract

New cellular functions and developmental processes can evolve by modifying existing genes or creating novel genes. Novel genes can arise not only via duplication or mutation but also by acquiring foreign DNA, also called horizontal gene transfer (HGT). Here we show that HGT likely contributed to the creation of a novel gene indispensable for reproduction in some insects. Long considered a novel gene with unknown origin, oskar has evolved to fulfil a crucial role in insect germ cell formation. Our analysis of over 100 insect Oskar sequences suggests that Oskar arose de novo via fusion of eukaryotic and prokaryotic sequences. This work shows that highly unusual gene origin processes can give rise to novel genes that can facilitate evolution of novel developmental mechanisms.One Sentence SummaryOur research shows that gene origin processes often considered highly unusual, including HGT and de novo coding region evolution, can give rise to novel genes that can both participate in pre-existing gene regulatory networks, and also facilitate the evolution of novel developmental mechanisms.

LOTUS-domain proteins - developmental effectors from a molecular perspective

“…Short Oskar carries a dimerizing eLOTUS domain, which is connected by a disordered linker to an Oskarspecific OSK domain ( Figure 2). Interestingly, sequence analysis suggests that the OSK domain is of bacterial origin and that it has combined with the LOTUS domain to form Oskar through horizontal gene transfer (Blondel et al 2020). The structure of the OSK domain resembles that of SGNH hydrolases (Jeske et al 2015;Yang et al 2015), a group of enzymes that catalyze the hydrolysis of ester bonds of various substrates, such as lipids, carbohydrates, and peptides (Akoh et al 2004).…”

Shared Cell Biological Functions May Underlie Pleiotropy of Molecular Interactions in the Germ Lines and Nervous Systems of Animals

“…Short Osk localizes to electrondense organelles called polar granules and recruits products of genes required for germ cell and posterior identity specification including vasa, nanos, and piwi (see below) (Markussen et al, 1995;Breitwieser et al, 1996;Vanzo et al, 2007). Although osk likely evolved in a last common insect ancestor (Lynch et al, 2011;Ewen-Campen et al, 2012;Blondel et al, 2020), the Long Osk domain and isoform appear to have evolved only within the Diptera (Blondel et al, 2020).…”

A symbiont's guide to the germline

“…Psyllid genomes contain metabolic genes from many different bacteria that complement symbiont pathways [128] , and aphid genomes contain non-Buchnera genes whose products are transferred to the Buchnera symbionts [97] . Furthermore, in a recent preprint, Blondel et al propose that the oskar gene, which is necessary and sufficient to induce the formation of the germline in holometabolous insects, is the product of a horizontal gene transfer event combined with a fusion event between a bacterial gene and a eukaryotic gene [7] . Thus, germline-associated endosymbionts may even be implicated in the formation of the germline itself.…”