Richardson, A. E. | Search bioRxiv

bioRxiv2021

The RNA helicase DHX36/G4R1 modulates C9orf72 GGGGCC repeat-associated translation

GGGGCC (G4C2) hexanucleotide repeat expansions (HRE) in C9orf72 are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Repeat-associated non-AUG (RAN) translation of this expansion generates toxic proteins that accumulate in patient brains and contribute to disease pathogenesis. The DEAH-Box Helicase 36 (DHX36/G4R1) plays active roles in RNA and DNA G-quadruplex (G4) resolution in cells. As G4C2 repeats form G4 structures in vitro, we sought to determine the impact of manipulating DHX36 expression on repeat transcription and RAN translation. We found that DHX36 depletion suppresses RAN translation from reporter constructs in a repeat length dependent manner while overexpression of DHX36 enhances RAN translation from G4C2 reporter RNAs. Taken together, these results suggest that DHX36 is active in regulating G4C2 repeat translation, providing potential implications for therapeutic development in nucleotide repeats expansion disorders.

molecular biology↗

bioRxiv2020

A novel microcosm for recruiting inherently competitive biofertilizer-candidate microorganisms from soil environments

Fertilizer phosphorus (P) is both a necessary crop nutrient and finite resource, necessitating the development of innovative solutions for P fertilizer efficiency and recycling in agricultural systems. Myo-inositol hexakisphosphate (phytate) and its lower order derivatives constitute the majority of identified organic P in many soil types and has been shown to accumulate with increasing application of P fertilizer. Phytate is only poorly available to plants, and in alkaline soils it often precipitated as even more unavailable calcium (Ca)-phytate. Incorporating phytase-producing biofertilizers (i.e., microbial-based products with capacity to mineralize phytate) into soil presents a viable and environmentally acceptable way of utilizing P from phytate, whilst reducing the need for mineral P application. Here we present an in-soil microcosm that utilizes precipitated Ca-phytate to recruit microorganisms with degradation activity towards phytate in solum. Our results show both direct and indirect evidence for Ca-phytate mineralization in vitro and in solum. Furthermore, the abundance of bacteria recruited was measured via 16S rRNA gene copy number, as was three genes relating to organic P degradation; phoX and phoD phosphatases and the BPP ({beta}-propeller phytase) gene. Amplicon sequencing as well as BioLog catabolism studies show that microcosm treatments containing the bait Ca-phytate, recruited a different set of microorganisms when compared to controls. These Ca-phytate microcosms recruited mainly Actinobacteria, Firmicutes, and Proteobacteria, and the genus Streptomyces was specifically enriched. We conclude that our microcosm presents an innovative approach for isolating soil microorganisms with the potential to degrade precipitated phytate in solum and represents a new isolation method with the potential to isolate inherently robust biofertilizer candidates directly from target soils.

ecology↗