Advertisement

 

 

The heme-regulatory motif of nuclear receptor Rev-erbβ is a key mediator of heme and redox signaling in circadian rhythm maintenance and metabolism.

The heme-regulatory motif of nuclear receptor Rev-erbβ is a key mediator of heme and redox signaling in circadian rhythm maintenance and metabolism.
Author Information (click to view)

Carter EL, Ramirez Y, Ragsdale SW,


Carter EL, Ramirez Y, Ragsdale SW, (click to view)

Carter EL, Ramirez Y, Ragsdale SW,

Advertisement
Share on FacebookTweet about this on TwitterShare on LinkedIn

The Journal of biological chemistry 2017 05 12292(27) 11280-11299 doi 10.1074/jbc.M117.783118

Abstract

Rev-erbβ is a heme-responsive transcription factor that regulates genes involved in circadian rhythm maintenance and metabolism, effectively bridging these critical cellular processes. Heme binding to Rev-erbβ indirectly facilitates its interaction with the nuclear receptor co-repressor (NCoR1), resulting in repression of Rev-erbβ target genes. Fe(3+)-heme binds in a 6-coordinate complex with axial His and Cys ligands, the latter provided by a heme-regulatory motif (HRM). Rev-erbβ was thought to be a heme sensor based on a weak Kd value for the Rev-erbβ·heme complex of 2 μm determined with isothermal titration calorimetry. However, our group demonstrated with UV-visible difference titrations that the Kd value is in the low nanomolar range, and the Fe(3+)-heme off-rate is on the order of 10(-6) s(-1) making Rev-erbβ ineffective as a sensor of Fe(3+)-heme. In this study, we dissected the kinetics of heme binding to Rev-erbβ and provided a Kd for Fe(3+)-heme of ∼0.1 nm Loss of the HRM axial thiolate via redox processes, including oxidation to a disulfide with a neighboring cysteine or dissociation upon reduction of Fe(3+)- to Fe(2+)-heme, decreased binding affinity by >20-fold. Furthermore, as measured in a co-immunoprecipitation assay, substitution of the His or Cys heme ligands in Rev-erbβ was accompanied by a significant loss of NCoR1 binding. These results demonstrate the importance of the Rev-erbβ HRM in regulating interactions with heme and NCoR1 and advance our understanding of how signaling through HRMs affects the major cellular processes of circadian rhythm maintenance and metabolism.

Submit a Comment

Your email address will not be published. Required fields are marked *

14 + 3 =

[ HIDE/SHOW ]