Investigating the transcriptional regulatory role of FBXA-215 [embryos]

We identified a Mariner transposase helix-turn-helix (HTH) DNA-binding domain that was captured in the Caenorhabditis genus by a subset of F-box genes, which we refer to as F-box A2 genes. The origin of F-box A2 genes likely occurred through a single transposase capture event, followed by an increase in copy number. We focused on fbxa-215, a F-box A2 gene highly expressed in the C. elegans germline and embryos, and that localizes to germ granules in embryos. The HTH domain of FBXA-215 is required for fertility and displays predominantly a signature of purifying selection, highlighting the importance of this domain. As the HTH domain of FBXA-215 is related to the DNA-binding HTH domain of transposases, we reasoned that FBXA-215 may bind to DNA in C. elegans and thus regulate gene expression at the transcriptional level. We performed mRNA sequencing of young adults and embryos to test this, but found no clear deregulation of protein-coding genes and transposable elements upon complete deletion of fbxa-215. Overall design: To test whether FBXA-215 has a role in regulating gene expression at the transcriptional level, we have sequenced mRNAs of mixed-staged embryos and young adults of wild-type N2 and fbxa-215(syb4404) mutants grown at 20 and 25oC.