Unique Heme Environmental Structures in Heme-regulated Proteins Using Heme as the Signaling Molecule

Ishimori, Koichiro; Watanabe, Yuta

doi:10.1246/cl.140787

Cited by 14 publications

(11 citation statements)

References 93 publications

(97 reference statements)

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“…Firstly, we used a previously well-established method to characterize reversible heme binding to these proteins ( 35 , 57 ). It is worth noting that heme-protein interactions mediating signaling or regulation is often dynamic, reversible and transient.…”

Section: Resultsmentioning

confidence: 99%

Heme promotes transcriptional and demethylase activities of Gis1, a member of the histone demethylase JMJD2/KDM4 family

Lal

Comer

Konduri

et al. 2017

Nucleic Acids Research

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The yeast Gis1 protein is a transcriptional regulator belonging to the JMJD2/KDM4 subfamily of demethylases that contain a JmjC domain, which are highly conserved from yeast to humans. They have important functions in histone methylation, cellular signaling and tumorigenesis. Besides serving as a cofactor in many proteins, heme is known to directly regulate the activities of proteins ranging from transcriptional regulators to potassium channels. Here, we report a novel mechanism governing heme regulation of Gis1 transcriptional and histone demethylase activities. We found that two Gis1 modules, the JmjN + JmjC domain and the zinc finger (ZnF), can bind to heme specifically in vitro. In vivo functional analysis showed that the ZnF, not the JmjN + JmjC domain, promotes heme activation of transcriptional activity. Likewise, measurements of the demethylase activity of purified Gis1 proteins showed that full-length Gis1 and the JmjN + JmjC domain both possess demethylase activity. However, heme potentiates the demethylase activity of full-length Gis1, but not that of the JmjN + JmjC domain, which can confer heme activation of transcriptional activity in an unrelated protein. These results demonstrate that Gis1 represents a novel class of multi-functional heme sensing and signaling proteins, and that heme binding to the ZnF stimulates Gis1 demethylase and transcriptional activities.

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Section: Resultsmentioning

confidence: 99%

Heme promotes transcriptional and demethylase activities of Gis1, a member of the histone demethylase JMJD2/KDM4 family

Lal

Comer

Konduri

et al. 2017

Nucleic Acids Research

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“…These include fatty acid-binding proteins (FABPs), glutathione S-transferases (GSTs), and heme-binding proteins with a molecular mass of 23 kDa (HBP23) [9,11]. Both GSTs and HBP23 have a Cys-Pro (CP) motif, which is one of the heme regulatory motifs and is found in a wide variety of proteins whose function is regulated by heme [12,13]. The Cys residue in the CP motif is a heme ligand.…”

Section: Introductionmentioning

confidence: 99%

Dual role of the active-center cysteine in human peroxiredoxin 1: Peroxidase activity and heme binding

Watanabe

Ishimori

Uchida

2017

Biochemical and Biophysical Research Communications

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HBP23, a 23-kDa heme-binding protein identified in rats, is a member of the peroxiredoxin (Prx) family, the primary peroxidases involved in hydrogen peroxide catabolism. Although HBP23 has a characteristic Cys-Pro heme-binding motif, the significance of heme binding to Prx family proteins remains to be elucidated. Here, we examined the effect of heme binding to human peroxiredoxin-1 (PRX1), which has 97% amino acid identity to HBP23. PRX1 was expressed in Escherichia coli and purified to homogeneity. Spectroscopic titration demonstrated that PRX1 binds heme with a 1:1 stoichiometry and a dissociation constant of 0.17 μM. UV-vis spectra of heme-PRX1 suggested that Cys52 is the axial ligand of ferric heme. PRX1 peroxidase activity was lost upon heme binding, reflecting the fact that Cys52 is not only the heme-binding site but also the active center of peroxidase activity. Interestingly, heme binding to PRX1 caused a decrease in the toxicity and degradation of heme, significantly suppressing H 2 O 2 -dependent heme peroxidase activity and degradation of PRX1-bound heme compared with that of free hemin. By virtue of its cytosolic abundance (~20 μM), PRX1 thus functions as a scavenger of cytosolic hemin (<1 μM). Collectively, our results indicate that PRX1 has a dual role; Cys-dependent peroxidase activity and cytosolic heme scavenger.

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“…Irr forms a complex with the heme biosynthetic enzyme ferrochelatase, and therefore, Irr responds to the status of heme at the site of synthesis 6 . Our previous studies show that Irr has two heme binding sites 5 7 8 , and this binding is supposed to trigger Irr degradation by a mechanism that involves oxidative modification of the protein.…”

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confidence: 99%

Protein oxidation mediated by heme-induced active site conversion specific for heme-regulated transcription factor, iron response regulator

Kitatsuji

Izumi

Nambu

et al. 2016

Sci Rep

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The Bradyrhizobium japonicum transcriptional regulator Irr (iron response regulator) is a key regulator of the iron homeostasis, which is degraded in response to heme binding via a mechanism that involves oxidative modification of the protein. Here, we show that heme-bound Irr activates O2 to form highly reactive oxygen species (ROS) with the “active site conversion” from heme iron to non-heme iron to degrade itself. In the presence of heme and reductant, the ROS scavenging experiments show that Irr generates H2O2 from O2 as found for other hemoproteins, but H2O2 is less effective in oxidizing the peptide, and further activation of H2O2 is suggested. Interestingly, we find a time-dependent decrease of the intensity of the Soret band and appearance of the characteristic EPR signal at g = 4.3 during the oxidation, showing the heme degradation and the successive formation of a non-heme iron site. Together with the mutational studies, we here propose a novel “two-step self-oxidative modification” mechanism, during which O2 is activated to form H2O2 at the heme regulatory motif (HRM) site and the generated H2O2 is further converted into more reactive species such as ·OH at the non-heme iron site in the His-cluster region formed by the active site conversion.

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Unique Heme Environmental Structures in Heme-regulated Proteins Using Heme as the Signaling Molecule

Cited by 14 publications

References 93 publications

Heme promotes transcriptional and demethylase activities of Gis1, a member of the histone demethylase JMJD2/KDM4 family

Heme promotes transcriptional and demethylase activities of Gis1, a member of the histone demethylase JMJD2/KDM4 family

Dual role of the active-center cysteine in human peroxiredoxin 1: Peroxidase activity and heme binding

Protein oxidation mediated by heme-induced active site conversion specific for heme-regulated transcription factor, iron response regulator

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