Project description:Metagenome data from soil samples were collected at 0 to 10cm deep from 2 avocado orchards in Channybearup, Western Australia, in 2024. Amplicon sequence variant (ASV) tables were constructed based on the DADA2 pipeline with default parameters.
Project description:Data-dependent LC-MS/MS was used to generate a protein inventory of an affinity-purified assembly intermediate of the small subunit (SSU) of the Trypanosoma brucei mitochondrial ribosome. The identified proteins (mitoribosomal proteins and putative maturation factors) were then used to assist in solving the structure of the SSU assemblosome by cryo-electron microscopy.
Project description:The multi-layered nucleolus serves as the primary site of ribosome biogenesis, where successive maturation of small (SSU) and large (LSU) ribosomal subunit precursors occur. However, the spatio-functional relationship between pre-rRNA processing and nucleolar substructures and how this adapts to changing cellular physiological demands have remained incompletely understood. Here, our spatiotemporal analyses revealed a compartment-specific ribosomal subunit processing in human nucleoli, with SSU processomes maintained in fibrillar center/dense fibrillar component/periphery dense fibrillar component (FC/DFC/PDFC) domains while LSU pre-rRNAs largely transited to PDFC/granular component (GC) regions. Slow proliferating cells exhibited unexpected 5' external transcribed space (5' ETS)-centered SSU processing impairment, accompanied by FC/DFC structural remodeling and retarded SSU outflux. Direct 5' ETS processing perturbation at least partially recapitulated these FC/DFC alterations, supporting the functional interdependence between SSU processing and nucleolar architecture. Notably, anamniote bipartite nucleoli with merged FC/DFC compartments, exhibited distinct 5' ETS distribution and slower pre-rRNA flux compared to multi-layered nucleoli in amniotes. Introducing a FC/DFC interface to bipartite nucleoli enhanced processing efficiency, indicating that evolutionary emergence of nested FC/DFC may have optimized pre-rRNA processing. Collectively, depicting the spatiotemporal distribution of pre-rRNAs revealed an essential role of 5' ETS-centered SSU processing in maintaining nucleolar substructures and suggested a possible evolutionary advantage of the multi-layered structure in amniotes.
