» Articles » PMID: 27766492

CO and NO Bind to Fe(II) DiGeorge Critical Region 8 Heme but Do Not Restore Primary MicroRNA Processing Activity

Overview
Publisher Springer
Specialty Biochemistry
Date 2016 Oct 22
PMID 27766492
Citations 4
Authors
Affiliations
Soon will be listed here.
Abstract

The RNA-binding heme protein DiGeorge critical region 8 (DGCR8) and its ribonuclease partner Drosha cleave primary transcripts of microRNA (pri-miRNA) as part of the canonical microRNA (miRNA) processing pathway. Previous studies show that bis-cysteine thiolate-coordinated Fe(III) DGCR8 supports pri-miRNA processing activity, while Fe(II) DGCR8 does not. In this study, we further characterized Fe(II) DGCR8 and tested whether CO or NO might bind and restore pri-miRNA processing activity to the reduced protein. Fe(II) DGCR8 RNA-binding heme domain (Rhed) undergoes a pH-dependent transition from 6-coordinate to 5-coordinate, due to protonation and loss of a lysine ligand; the ligand bound throughout the pH change is a histidine. Fe(II) Rhed binds CO and NO from 6- and 5-coordinate states, forming common CO and NO adducts at all pHs. Fe(II)-CO Rhed is 6-coordinate, low-spin, and pH insensitive with the histidine ligand retained, suggesting that the protonatable lysine ligand has been replaced by CO. Fe(II)-NO Rhed is 5-coordinate and pH insensitive. Fe(II)-NO also forms slowly upon reaction of Fe(III) Rhed with excess NO via a stepwise process. Heme reduction by NO is rate-limiting, and the rate would be negligible at physiological NO concentrations. Importantly, in vitro pri-miRNA processing assays show that both CO- and NO-bound DGCR8 species are inactive. Fe(II), Fe(II)-CO, and Fe(II)-NO Rhed do not bear either of the cysteine ligands found in the Fe(III) state. These data support a model in which the bis-cysteine thiolate ligand environment of Fe(III) DGCR8 is necessary for establishing proper pri-miRNA binding and enabling processing activity.

Citing Articles

Gas-sensing riboceptors.

Anbalagan S RNA Biol. 2024; 21(1):1-6.

PMID: 39016047 PMC: 11259077. DOI: 10.1080/15476286.2024.2379607.


Carbon Monoxide Signaling: Examining Its Engagement with Various Molecular Targets in the Context of Binding Affinity, Concentration, and Biologic Response.

Yuan Z, De La Cruz L, Yang X, Wang B Pharmacol Rev. 2022; 74(3):823-873.

PMID: 35738683 PMC: 9553107. DOI: 10.1124/pharmrev.121.000564.


A metal-supported single-atom catalytic site enables carbon dioxide hydrogenation.

Hung S, Xu A, Wang X, Li F, Hsu S, Li Y Nat Commun. 2022; 13(1):819.

PMID: 35145110 PMC: 8831533. DOI: 10.1038/s41467-022-28456-9.


Heme enables proper positioning of Drosha and DGCR8 on primary microRNAs.

Partin A, Ngo T, Herrell E, Jeong B, Hon G, Nam Y Nat Commun. 2017; 8(1):1737.

PMID: 29170488 PMC: 5700927. DOI: 10.1038/s41467-017-01713-y.

References
1.
Krol J, Loedige I, Filipowicz W . The widespread regulation of microRNA biogenesis, function and decay. Nat Rev Genet. 2010; 11(9):597-610. DOI: 10.1038/nrg2843. View

2.
Marvin K, Reinking J, Lee A, Pardee K, Krause H, Burstyn J . Nuclear receptors homo sapiens Rev-erbbeta and Drosophila melanogaster E75 are thiolate-ligated heme proteins which undergo redox-mediated ligand switching and bind CO and NO. Biochemistry. 2009; 48(29):7056-71. PMC: 2849663. DOI: 10.1021/bi900697c. View

3.
Ferraroni M, Tilli S, Briganti F, Chegwidden W, Supuran C, Wiebauer K . Crystal structure of a zinc-activated variant of human carbonic anhydrase I, CA I Michigan 1: evidence for a second zinc binding site involving arginine coordination. Biochemistry. 2002; 41(20):6237-44. DOI: 10.1021/bi0120446. View

4.
Dhawan I, Shelver D, Thorsteinsson M, Roberts G, Johnson M . Probing the heme axial ligation in the CO-sensing CooA protein with magnetic circular dichroism spectroscopy. Biochemistry. 1999; 38(39):12805-13. DOI: 10.1021/bi991303c. View

5.
Du J, Perera R, Dawson J . Alkylamine-ligated H93G myoglobin cavity mutant: a model system for endogenous lysine and terminal amine ligation in heme proteins such as nitrite reductase and cytochrome f. Inorg Chem. 2011; 50(4):1242-9. PMC: 3047591. DOI: 10.1021/ic101644u. View