Project description:MicroRNAs (miRNAs) are important regulators of gene expression. Their levels are precisely controlled through modulating the activity of the microprocesser complex (MC). Here we report that JANUS, a homology of the conserved U2 snRNP assembly factor in yeast and human, is required for miRNA accumulation. JANUS associates with MC components Dicer-like 1 and SERRATE (SE) and directly binds the stem-loop of pri-miRNAs. In a hypomorphic janus mutant, the activity of DCL1, the numbers of MC, and the interaction of primary miRNA transcript (pri-miRNAs) with MC are reduced. These data suggest that JANUS promotes the assembly and activity of MC through its interaction with MC and/or pri-miRNAs. In addition, JANUS modulates the transcription of some pri-miRNAs as it binds the promoter of pri-miRNAs and promotes Pol II occupancy of at their promoters. Moreover, global splicing defects are detected in janus. Taken together, our study reveals a novel role of a conserved splicing factor in miRNA biogenesis.
Project description:Competition between bacteria can impact the ability to colonize a host. In the accessory nidamental gland (ANG) reproductive symbiosis of the Hawaiian bobtail squid, Euprymna scolopes, symbionts colonize various epithelium lined tubules of adult females. We hypothesize that symbionts may use competitive mechanisms to determine ANG tubule colonization outcomes. One ANG strain, Leisingera sp. ANG-M7, was found to inhibit another ANG symbiont, Leisingera sp. ANG-DT, in vitro. Transposon mutagenesis was used to determine the genes required for this antimicrobial activity. Seven ANG-M7 transposon mutants were found with significantly decreased ability to inhibit ANG-DT compared to WT ANG-M7. Of these mutants, three strains (P08F1, P24E3, P40B12) were selected for transcriptome sequencing to look for shared pathways that were significantly different from WT.