The role of microtubule-dependent mRNA transport during polar growth of Ustilago maydis

• Applicant: Professor Dr. Michael Feldbrügge
• Subject Area: Plant Genetics and Genomics
• Term: from 2005 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 22278661

Ustilago maydis causes smut disease on corn. Recently, we demonstrated that RNAbinding proteins are implicated in pathogenicity. In particular, deletion of rrm4 led to impaired filament formation and reduced virulence. This gene encodes a RNAbinding protein with a novel domain architecture containing three N-terminal RNA recognition motives (RRMs) in combination with a C-terminal PABC domain (Poly (A)-binding protein C terminus) known as protein interaction interface. Mutational analysis of Rrm4 domains revealed that the N-terminal tandem RRMs most likely constitute the RNA-binding domain. The RNA binding activity of Rrm4 was confirmed in vivo performing UV cross-linking experiments. Subcellular localisation of Rrm4 fused to the green fluorescent protein (eGfp) showed that Rrm4-eGfp is assembled into particles that shuttle along microtubules and that particle formation depends on the PABC domain. Thus, we hypothesize that Rrm4-containing ribonucleoprotein (RNP) particles participate in microtubule-dependent RNA transport, a process that is important for polar growth of the infectious filament. In this proposal we want to identify the molecular cargo and the composition of transport particles including molecular motors. Unravelling the function of the cellular factors will deepen our understanding on long distance transport mediated by RNP particles as well as provide novel insights into cellular processes involved in pathogenicity of microorganisms.

• DFG Programme: Research Grants