000165611 001__ 165611 000165611 005__ 20260112132217.0 000165611 0247_ $$2doi$$a10.1038/s41598-025-88468-5 000165611 0248_ $$2sideral$$a147256 000165611 037__ $$aART-2025-147256 000165611 041__ $$aeng 000165611 100__ $$0(orcid)0000-0001-6107-1572$$aAlmada, Juan Cruz$$uUniversidad de Zaragoza 000165611 245__ $$aAllosteric coupling activation mechanism in histidine kinases 000165611 260__ $$c2025 000165611 5060_ $$aAccess copy available to the general public$$fUnrestricted 000165611 5203_ $$aHistidine kinases (HKs) are crucial regulators of cellular functions, mediating the phosphorylation of specific proteins to modulate their activity and localization. Upon signal detection, HKs transfer a phosphate group from ATP to a conserved histidine residue within their Dimerization and Histidine phosphotransfer domain, subsequently passing the phosphate to a response regulator (RR) that typically interacts with DNA promoters to regulate gene expression. This study investigates the signal transduction mechanism of Bacillus subtilis HK DesK. We generated substitutions on the conserved phospho-acceptor histidine and evaluated their effects on DesK’s activity in both in vivo and in vitro contexts. Notably, we found that a variant of DesK lacking the conserved histidine could still activate gene expression. Furthermore, computational simulations of DesK variants complexed with DesR revealed interactions that could be required to maintain DesR’s active conformation. Our findings elucidate an alternative pathway for RR activation via an allosteric mechanism that operates independently of histidine phosphorylation. We also demonstrated that Escherichia coli HK EnvZ, when lacking the conserved histidine, can activate gene expression. This HK-Allosteric Coupling Activation Mechanism functions without reliance on phosphorylation or ATP consumption, potentially serving as a fail-safe mechanism under nutrient-limited conditions. 000165611 540__ $$9info:eu-repo/semantics/openAccess$$aby-nc-nd$$uhttps://creativecommons.org/licenses/by-nc-nd/4.0/deed.es 000165611 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000165611 700__ $$aBortolotti, Ana 000165611 700__ $$aPorrini, Lucía 000165611 700__ $$aAlbanesi, Daniela 000165611 700__ $$aMiguel, Virginia 000165611 700__ $$aCybulski, Larisa 000165611 7102_ $$12013$$2765$$aUniversidad de Zaragoza$$bDpto. Química Orgánica$$cÁrea Química Orgánica 000165611 773__ $$g15, 1 (2025), 14682 [13 pp.]$$pSci. rep. (Nat. Publ. Group)$$tScientific reports (Nature Publishing Group)$$x2045-2322 000165611 8564_ $$s2548900$$uhttps://zaguan.unizar.es/record/165611/files/texto_completo.pdf$$yVersión publicada 000165611 8564_ $$s2721749$$uhttps://zaguan.unizar.es/record/165611/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000165611 909CO $$ooai:zaguan.unizar.es:165611$$particulos$$pdriver 000165611 951__ $$a2026-01-12-11:11:10 000165611 980__ $$aARTICLE