{'fraction_non_alphanumeric': 0.019184652278177457, 'fraction_numerical': 0.003357314148681055, 'mean_word_length': 5.930232558139535, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Arabidopsis protein arginine methyltransferase 3 is required for ribosome biogenesis by affecting precursor ribosomal RNA processing

Significance The functional relationship between protein arginine methyltransferases (PRMTs) and ribosome biogenesis was proposed a decade ago, but the underlying mechanism still remains elusive. In this work, we demonstrate for the first time to our knowledge that the coexistence of two pre-rRNA processing pathways is conserved in plants; and Arabidopsis PRMT3 is required for the balance between these pathways. These findings uncover an important link between PRMT and proper pre-rRNA processing, which not only extends our understanding of the regulatory scope of PRMTs but also reveals the complexity of regulation of ribosome biogenesis. The alternative pre-rRNA processing pathways in plants modulated by PRMT3 may be conserved in other multicellular organisms, thereby shedding light on PRMT functions and regulation of ribosome biogenesis in animals. Ribosome biogenesis is a fundamental and tightly regulated cellular process, including synthesis, processing, and assembly of rRNAs with ribosomal proteins. Protein arginine methyltransferases (PRMTs) have been implicated in many important biological processes, such as ribosome biogenesis. Two alternative precursor rRNA (pre-rRNA) processing pathways coexist in yeast and mammals; however, how PRMT affects ribosome biogenesis remains largely unknown. Here we show that Arabidopsis PRMT3 (AtPRMT3) is required for ribosome biogenesis by affecting pre-rRNA processing. Disruption of AtPRMT3 results in pleiotropic developmental defects, imbalanced polyribosome profiles, and aberrant pre-rRNA processing. We further identify an alternative pre-rRNA processing pathway in Arabidopsis and demonstrate that AtPRMT3 is required for the balance of these two pathways to promote normal growth and development. Our work uncovers a previously unidentified function of PRMT in posttranscriptional regulation of rRNA, revealing an extra layer of complexity in the regulation of ribosome biogenesis.