The Wide Distribution and Horizontal Transfers of Beta Satellite DNA in Eukaryotes

Abstract Beta satellite DNA (satDNA) sequences, also known as Sau3A sequences, are repeated DNA elements reported in human and primate genomes. Beta satDNAs may play roles in genome stability and chromosome segregation during mitosis. It is previously thought that beta satDNAs originated in old world monkeys and bursted in great apes. However, global and high-throughput studies on beta satDNAs are still absent. Results: In this study, we searched 7,821 genome assemblies of 3,767 eukaryotic species and found that beta satDNAs actually are widely distributed across eukaryotes. The four major branches of eukaryotes, animals, fungi, plants and Harosa/SAR, all have multiple clades containing beta satDNAs. These results were also confirmed by searching whole genome sequencing data (SRA) and PCR assay. Beta satDNA might have originated during the early evolution of eukaryotes. The widely patchy distribution of beta satDNAs across eukaryotes presents a typical scenario of multiple horizontal transfers (HT). In contrast, beta satDNA sequences were found in all the primate clades, Primatomorpha and Euarchonta, indicating an origin in the common ancestor and vertical transfers thereafter. Besides in eukaryotes, beta satDNAs were even found in some archaea and bacteria, which should have been acquired from eukaryotes via HTs. Conclusion: Beta satDNAs widely exist in eukaryotes. The current distribution landscape of beta satDNA is the result of countless HTs. Our study shows for the first time that satellite DNAs can also undergo HT, and will provide new ideas for the future investigations in HT/HGT field. Keywords: Beta satellite DNA, Sau3A sequences, Eukaryotes, Horizontal gene transfer, Primates