Biology subjects

Jeschke, G.

Publications and source records attributed to Jeschke, G..

2 recordsLinked to original sources

bioRxiv2021

Spectroscopic glimpses of the transition state of ATP hydrolysis trapped in a bacterial DnaB helicase

The ATP hydrolysis transition state of motor proteins is a weakly populated protein state that can be stabilized and investigated by replacing ATP with chemical mimics. We present atomic-level structural and dynamic insights on a state created by ADP aluminum fluoride binding to the bacterial DnaB helicase from Helicobacter pylori. We determined the positioning of the metal ion cofactor within the active site using electron paramagnetic resonance, and identified the protein protons coordinating to the phosphate groups of ADP and DNA using proton-detected 31P,1H solid-state nuclear magnetic resonance spectroscopy at fast magic-angle spinning > 100 kHz, as well as temperature-dependent proton chemical-shift values to prove their engagements in hydrogen bonds. 19F and 27Al MAS NMR spectra reveal a highly mobile, fast-rotating aluminum fluoride unit pointing to the capture of a late ATP hydrolysis translation state in which the phosphoryl unit is already detached from the arginine and lysine fingers.

biophysics↗

bioRxiv2021

Gradual opening of Smc arms in prokaryotic condensin

Multi-subunit SMC ATPases control chromosome superstructure apparently by catalyzing a DNA-loop-extrusion reaction. SMC proteins harbor an ABC-type ATPase head and a hinge dimerization domain connected by a coiled coil arm. Two arms in a SMC dimer can co-align, thereby forming a rod-shaped particle. Upon ATP binding, SMC heads engage, and arms are thought to separate. Here, we studied the shape of B. subtilis Smc-ScpAB by electron-spin resonance spectroscopy. Arm separation was readily detected proximal to the heads in the absence of ligands, while separation near the hinge largely depended on ATP and DNA. Artificial blockage of arm opening eliminated DNA stimulation of ATP hydrolysis, but did not prevent basal ATPase activity. We identified an arm-to-arm contact as being important for controlling the molecular transformations. Point mutations at this arm interface eliminate Smc function. We propose that partially open, intermediary conformations provide directionality to SMC DNA translocation by binding suitable DNA substrates.

biochemistry↗