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: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.
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:Ribosome small subunit (SSU) is assembled by the SSU processome which contains approximately 70 non-ribosomal protein factors. The biochemical mechanism for the SSU processome in 18S rRNA processing and maturation has been extensively studied, however, how the SSU processome components enter to the nucleolus has not been systematically investigated. Here we checked the nucleolar localization of 50 human SSU processome components and find that UTP3 and other 24 proteins enter to the nucleolus autonomously. For the remaining 25 proteins we find that UTP3/SAS10 assists the nucleolar localization of five proteins, namely MPP10, UTP25, EMG1 and two UTP-B components UTP12 and UTP13, and this ferry function of UTP3 is conserved in zebrafish. We also find that knockdown of human UTP3 impairs the cleavage at A0-site while loss-of-function of either utp3/sas10 or utp13/tbl3 in zebrafish causes an accumulation of the processed products containing the 5′ETS, supporting the crucial role of UTP3 in mediating the 5′ETS processing and degradation. Moreover, UTP3 directly interacts with and delivers EXOSC10 into the nucleolus, suggesting that UTP3 may play a direct role in recruiting the nuclear exosome to the SSU processome for degradation of the processed 5′ETS. These findings lay the ground for studying the mechanism of cytoplasm-to-nucleolus trafficking of the SSU processome components and the multifaceted roles of UTP3 during pre-rRNA processing.