Elucidating the autophosphorylation mechanism of the histidine kinase DesK

DODES TRAIAN, MARTÍN M.; OLIVIERI, FEDERICO A.; MARTÍ, MARCELO A.; JELIC, EDUARDO; WETZLER, DIANA E.

Congreso; L Reunión Anual de la Sociedad Argentina de Biofísica; 2022

Sociedad Argentina de Biofísica

Histidine kinases (HKs) are major players in bacterial signaling that autophosphorylate on a conserved histidine. HKs generally work as dimers. Each HK exhibits one of two possible mechanisms of autophosphorylation: Intramolecular (cis-acting) and intermolecular (trans-acting), where one subunit of the dimer phosphorylates itself or the other subunit respectively. It is known that this mechanism of autophosphorylation correlates with the left- or right-handedness of a particular loop in the dimerization and phosphohistidine domain (DHp), which produces a different overall structural organization for cis and trans HKs. There are 4 families of DHp: HisKA, HisKA_2, HisKA_3 and HWE_HK, with most HKs belonging to HisKA family. In addition, most structural information on the DHp domain belongs to HKs of the HisKA family. This makes it hard to extrapolate this structure-function correlation to other HK families. DesK from Bacillus subtilis is the only HK belonging to the HisKA_3 family for which structural information is available for its DHp domain, and it provides contradicting information. While its DHp conformation corresponds with that of a cis-acting HK, the position of its catalytic domain would suggest it autophosphorylates in trans. While there is some experimental evidence that suggests DesK indeed autophosphorylates in trans, it hasn’t been verified biochemically. If DesK autophosphorylates in trans it would be the first HK known to do so while having a left-handed DHp loop. In this work we set off to provide biochemical evidence of DesK’s mechanism of autophosphorylation.