Interplay between chromophore binding and domain assembly by the B₁₂-dependent photoreceptor protein, CarH

Abstract

Organisms across the natural world respond to their environment through the action of photoreceptor proteins. The vitamin B12-dependent photoreceptor, CarH, is a bacterial transcriptional regulator that controls the biosynthesis of...

Coenzyme B12‐dependent and independent photoregulation of carotenogenesis across Myxococcales

“…Extant oxygen‐binding haemoglobin tetramers, with their striking cooperativity and regulatory modes, may have evolved by successive gene duplication‐divergence events through surprisingly few mutations from an ancestral dimeric precursor, which itself arose from an ancient monomer (Pillai et al ., 2020 ). Single mutations at the interface between the two head‐to‐tail dimers that constitute the CarH Tt tetramer suffice to shift the tetramer to a native dimer, which retains AdoCbl‐dependent DNA binding, but with altered affinity and cooperativity (Jost et al ., 2015b ); CarH Tt tetramerization traces a kinetic pathway from monomer to dimer to tetramer (Camacho et al ., 2021 ). Hence, few genetic changes may underlie the shift between the AdoCbl‐dependent Cystobacter CarH dimer and its tetrameric homologues.…”

Ion Mobility Mass Spectrometry (IM-MS) for Structural Biology: Insights Gained by Measuring Mass, Charge, and Collision Cross Section

“…To crystallize this protein, the N and C termini had to be removed, resulting in a stable dimeric form, − which was often used as a proxy for the active protein. Here a hybrid IM-MS approach was used to analyze the conformations adopted by the full-length photoreceptor upon light activation. ,, Initial experiments tried UVPD to dissociate either the core domain or the wild-type (WT) dimer in the gas-phase. This was unsuccessful and only produced small fragments from the N and C termini.…”

“…Here a hybrid IM-MS approach was used to analyze the conformations adopted by the full-length photoreceptor upon light activation. 270,274,275 Initial experiments tried UVPD to dissociate either the core domain or the wild-type (WT) dimer in the gas-phase. This was unsuccessful and only produced small fragments from the N and C termini.…”

Biomolecular infrared spectroscopy: making time for dynamics

“…Ultrafast spectroscopies employing UV or visible wavelength excitation are ideally suited to the study of naturally occurring light activated proteins. 53,55,[74][75][76][77][78][79][80][81][82] This has been a rich eld of study and the intention is not to provide a comprehensive review, but to focus on the impacts of extended temporal range experiments and advanced probing methods.…”