Analysis of the Microprocessor in Dictyostelium: The Role of RbdB, a dsRNA Binding Protein

PLoS Genet. 2016 Jun 6;12(6):e1006057. doi: 10.1371/journal.pgen.1006057. eCollection 2016 Jun.


We identified the dsRNA binding protein RbdB as an essential component in miRNA processing in Dictyostelium discoideum. RbdB is a nuclear protein that accumulates, together with Dicer B, in nucleolar foci reminiscent of plant dicing bodies. Disruption of rbdB results in loss of miRNAs and accumulation of primary miRNAs. The phenotype can be rescued by ectopic expression of RbdB thus allowing for a detailed analysis of domain function. The lack of cytoplasmic dsRBD proteins involved in miRNA processing, suggests that both processing steps take place in the nucleus thus resembling the plant pathway. However, we also find features e.g. in the domain structure of Dicer which suggest similarities to animals. Reduction of miRNAs in the rbdB- strain and their increase in the Argonaute A knock out allowed the definition of new miRNAs one of which appears to belong to a new non-canonical class.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Argonaute Proteins / genetics*
  • Dictyostelium / genetics*
  • Ectopic Gene Expression / genetics
  • Gene Knockout Techniques
  • Green Fluorescent Proteins / genetics
  • MicroRNAs / genetics*
  • Nuclear Proteins / genetics
  • RNA, Double-Stranded / genetics*
  • RNA-Binding Proteins / genetics*
  • Ribonuclease III / genetics*


  • Argonaute Proteins
  • MicroRNAs
  • Nuclear Proteins
  • RNA, Double-Stranded
  • RNA-Binding Proteins
  • Green Fluorescent Proteins
  • Ribonuclease III

Grant support

This work was funded by a grant of the Deutsche Forschungsgemeinschaft (Ne285/14) to WN and a grant by the Deutsche Forschungsgemeinschaft (HA3459/5 and /14) to CH DM received a Doctoral stipend by the State of Hessia (via Kassel University) The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.