The structure of DarB in complex with Rel NTD reveals nonribosomal activation of Rel stringent factors

Autor: Andres Ainelo, Julien Caballero-Montes, Ondřej Bulvas, Karin Ernits, Kyo Coppieters ‘t Wallant, Hiraku Takada, Sophie Z. Craig, Gabriel Mazzucchelli, Safia Zedek, Iva Pichová, Gemma C. Atkinson, Ariel Talavera, Chloe Martens, Vasili Hauryliuk, Abel Garcia-Pino
Rok vydání: 2023
Předmět:
Zdroj: Science Advances. 9
ISSN: 2375-2548
DOI: 10.1126/sciadv.ade4077
Popis: Rel stringent factors are bifunctional ribosome-associated enzymes that catalyze both synthesis and hydrolysis of the alarmones (p)ppGpp. Besides the allosteric control by starved ribosomes and (p)ppGpp, Rel is regulated by various protein factors depending on specific stress conditions, including the c-di-AMP–binding protein DarB. However, how these effector proteins control Rel remains unknown. We have determined the crystal structure of the DarB 2 :Rel NTD 2 complex, uncovering that DarB directly engages the SYNTH domain of Rel to stimulate (p)ppGpp synthesis. This association with DarB promotes a SYNTH-primed conformation of the N-terminal domain region, markedly increasing the affinity of Rel for ATP while switching off the hydrolase activity of the enzyme. Binding to c-di-AMP rigidifies DarB, imposing an entropic penalty that precludes DarB-mediated control of Rel during normal growth. Our experiments provide the basis for understanding a previously unknown mechanism of allosteric regulation of Rel stringent factors independent of amino acid starvation.
Databáze: OpenAIRE