Maturation of 40S ribosomal subunits involves the cleavage of the fusion protein consisting of the ribosomal protein eS30 and the ubiquitin like protein FUBI. The Kutay lab gained insights into the mechanism of this process and identified the previously unkown protease responsible for the cleavage. Their findings have been published in eLIFE in the article entitled "Processing of the ribosomal ubiquitin-like fusion protein FUBI-eS30/FAU is required for 40S maturation and depends on USP36 "
Abstract
In humans and other holozoan organisms, the ribosomal protein eS30 is synthesized as a fusion protein with the ubiquitin-like protein FUBI. However, FUBI is not part of the mature 40S ribosomal subunit and cleaved off by an as-of-yet unidentified protease. How FUBI-eS30 processing is coordinated with 40S subunit maturation is unknown. To study the mechanism and importance of FUBI-eS30 processing, we expressed non-cleavable mutants in human cells, which affected late steps of cytoplasmic 40S maturation, including the maturation of 18S rRNA and recycling of late-acting ribosome biogenesis factors. Differential affinity purification of wild-type and non-cleavable FUBI-eS30 mutants identified the deubiquitinase USP36 as a candidate FUBI-eS30 processing enzyme. Depletion of USP36 by RNAi or CRISPRi indeed impaired FUBI-eS30 processing and moreover, purified USP36 cut FUBI-eS30 in vitro. Together, these data demonstrate the functional importance of FUBI-eS30 cleavage and identify USP36 as a novel protease involved in this process.
Read the Publication in eLife (Open Access)
Abstract, figure and title from van den Heuvel et al. (2021) eLife published under a CC BY 4.0 license.