Structural and Biochemical Characterization of the Frequency-interacting RNA Helicase from Neurospora crassa

Presenter Information

Keith OlsenFollow

Class

Article

Graduation Year

2021

College

College of Science

Department

Chemistry and Biochemistry Department

Faculty Mentor

Sean Johnson

Presentation Type

Poster Presentation

Abstract

The FRH (Frequency-interacting RNA helicase) protein is essential for life as well as for circadian rhythmicity in Neurospora crassa. The Neurospora FFC (Frequency-FRH) complex and the RNA exosome are part of a transcriptional negative feedback loop that regulates frq transcript levels and the circadian output pathway. However, the molecular mechanisms underlying these functions remain largely unknown. With 56% sequence identity and 73% similarity overall, Mtr4, the budding yeast homolog of FRH, is an important regulator of RNA metabolism in eukaryotes as a member of the TRAMP complex and essential activator of the nuclear exosome. In an effort to understand the molecular details of FRH function in RNA regulation, we have initiated structural and biochemical characterization of the FRH RNA helicase. Here, we present a 3.5 Å structure of FRH along with the first characterization of FRH RNA unwinding activity. The FRH structure reveals a core five-domain architecture highly similar to Mtr4. However, significant structural rearrangements in the arch domain of the FRH are observed. Unexpectedly, FRH forms a dimer in the crystal. While the biologically relevant form of FRH has been understood to be monomeric, it was recently reported that FRH can form higher-order multimeric states as part of the FFC complex. Ongoing work is aimed towards deciphering the biological significance of the FRH dimeric structure along with further characterization of preferred substrates for FRH RNA unwinding.

Location

North Atrium

Start Date

4-13-2017 10:30 AM

End Date

4-13-2017 11:45 AM

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Apr 13th, 10:30 AM Apr 13th, 11:45 AM

Structural and Biochemical Characterization of the Frequency-interacting RNA Helicase from Neurospora crassa

North Atrium

The FRH (Frequency-interacting RNA helicase) protein is essential for life as well as for circadian rhythmicity in Neurospora crassa. The Neurospora FFC (Frequency-FRH) complex and the RNA exosome are part of a transcriptional negative feedback loop that regulates frq transcript levels and the circadian output pathway. However, the molecular mechanisms underlying these functions remain largely unknown. With 56% sequence identity and 73% similarity overall, Mtr4, the budding yeast homolog of FRH, is an important regulator of RNA metabolism in eukaryotes as a member of the TRAMP complex and essential activator of the nuclear exosome. In an effort to understand the molecular details of FRH function in RNA regulation, we have initiated structural and biochemical characterization of the FRH RNA helicase. Here, we present a 3.5 Å structure of FRH along with the first characterization of FRH RNA unwinding activity. The FRH structure reveals a core five-domain architecture highly similar to Mtr4. However, significant structural rearrangements in the arch domain of the FRH are observed. Unexpectedly, FRH forms a dimer in the crystal. While the biologically relevant form of FRH has been understood to be monomeric, it was recently reported that FRH can form higher-order multimeric states as part of the FFC complex. Ongoing work is aimed towards deciphering the biological significance of the FRH dimeric structure along with further characterization of preferred substrates for FRH RNA unwinding.