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The structural and functional workings of KEOPS.

ABSTRACT: KEOPS (Kinase, Endopeptidase and Other Proteins of Small size) is a five-subunit protein complex that is highly conserved in eukaryotes and archaea and is essential for the fitness of cells and for animal development. In humans, mutations in KEOPS genes underlie Galloway-Mowat syndrome, which manifests in severe microcephaly and renal dysfunction that lead to childhood death. The Kae1 subunit of KEOPS catalyzes the universal and essential tRNA modification N6-threonylcarbamoyl adenosine (t6A), while the auxiliary subunits Cgi121, the kinase/ATPase Bud32, Pcc1 and Gon7 play a supporting role. Kae1 orthologs are also present in bacteria and mitochondria but function in distinct complexes with proteins that are not related in structure or function to the auxiliary subunits of KEOPS. Over the past 15 years since its discovery, extensive study in the KEOPS field has provided many answers towards understanding the roles that KEOPS plays in cells and in human disease and how KEOPS carries out these functions. In this review, we provide an overview into recent advances in the study of KEOPS and illuminate exciting future directions.

SUBMITTER: Beenstock J

PROVIDER: S-EPMC8565320 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Structural and functional characterization of KEOPS dimerization by Pcc1 and its role in t6A biosynthesis.

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Project description:The KEOPS complex, which is conserved across archaea and eukaryotes, is composed of four core subunits; Pcc1, Kae1, Bud32 and Cgi121. KEOPS is crucial for the fitness of all organisms examined. In humans, pathogenic mutations in KEOPS genes lead to Galloway-Mowat syndrome, an autosomal-recessive disease causing childhood lethality. Kae1 catalyzes the universal and essential tRNA modification N6-threonylcarbamoyl adenosine, but the precise roles of all other KEOPS subunits remain an enigma. Here we show using structure-guided studies that Cgi121 recruits tRNA to KEOPS by binding to its 3' CCA tail. A composite model of KEOPS bound to tRNA reveals that all KEOPS subunits form an extended tRNA-binding surface that we have validated in vitro and in vivo to mediate the interaction with the tRNA substrate and its modification. These findings provide a framework for understanding the inner workings of KEOPS and delineate why all KEOPS subunits are essential.

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