Distribution of heme in systems containing heme-free and heme-bound hemoglobin chains

Winterhalter, Kaspar H.; Ioppolo, Carmela; Antonini, Eraldo

doi:10.1021/bi00796a023

Cited by 23 publications

(14 citation statements)

References 19 publications

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“…After adding 2–5 mg of sodium dithionite, the absorption spectrum was recorded between 500 and 600 nm. Known extinction coefficients of the reduced pyridine hemochromogen of protoheme were used to calculate the heme concentrations .…”

Section: Methodsmentioning

confidence: 99%

Mechanism governing heme synthesis reveals a GATA factor/heme circuit that controls differentiation

et al. 2015

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Metal ion-containing macromolecules have fundamental roles in essentially all biological processes throughout the evolutionary tree. For example, iron-containing heme is a cofactor in enzyme catalysis and electron transfer and an essential hemoglobin constituent. To meet the intense demand for hemoglobin assembly in red blood cells, the cell type-specific factor GATA-1 activates transcription of Alas2, encoding the rate-limiting enzyme in heme biosynthesis, 5-aminolevulinic acid synthase-2 (ALAS-2). Using genetic editing to unravel mechanisms governing heme biosynthesis, we discovered a GATA factor-and heme-dependent circuit that establishes the erythroid cell transcriptome. CRISPR/Cas9-mediated ablation of two Alas2 intronic cis elements strongly reduces GATA-1-induced Alas2 transcription, heme biosynthesis, and surprisingly, GATA-1 regulation of other vital constituents of the erythroid cell transcriptome. Bypassing ALAS-2 function in Alas2 cis element-mutant cells by providing its catalytic product 5-aminolevulinic acid rescues heme biosynthesis and the GATA-1-dependent genetic network. Heme amplifies GATA-1 function by downregulating the heme-sensing transcriptional repressor Bach1 and via a Bach1-insensitive mechanism. Through this dual mechanism, heme and a master regulator collaborate to orchestrate a cell type-specific transcriptional program that promotes cellular differentiation.

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Section: Methodsmentioning

confidence: 99%

Mechanism governing heme synthesis reveals a GATA factor/heme circuit that controls differentiation

et al. 2015

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“…In vitro reconstitution studies suggest that HbA formation occurs through a series of monomeric, dimeric, and tetrameric intermediates that are partially saturated with heme (55,112,114,116) (Fig. 1, lower H subunit dimers, and (c) association of these dimers to form tetrameric HbA (5,37,74,75).…”

Section: Mollan Et Almentioning

confidence: 99%

The Role of Alpha-Hemoglobin Stabilizing Protein in Redox Chemistry, Denaturation, and Hemoglobin Assembly

Mollan

Weiss

et al. 2010

Antioxidants & Redox Signaling

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Hemoglobin biosynthesis in erythrocyte precursors involves several steps. The correct ratios and concentrations of normal alpha (a) and beta (b) globin proteins must be expressed; apoproteins must be folded correctly; heme must be synthesized and incorporated into these globins rapidly; and the individual a and b subunits must be rapidly and correctly assembled into heterotetramers. These events occur on a large scale in vivo, and dysregulation causes serious clinical disorders such as thalassemia syndromes. Recent work has implicated a conserved erythroid protein known as Alpha-Hemoglobin Stabilizing Protein (AHSP) as a participant in these events. Current evidence suggests that AHSP enhances a subunit stability and diminishes its participation in harmful redox chemistry. There is also evidence that AHSP facilitates one or more early-stage post-translational hemoglobin biosynthetic events. In this review, recent experimental results are discussed in light of several current models describing globin subunit folding, heme uptake, assembly, and denaturation during hemoglobin synthesis. Particular attention is devoted to molecular interactions with AHSP that relate to a chain oxidation and the ability of a chains to associate with partner b chains. Antioxid. Redox Signal. 12, 219-232.

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“…The question was whether the individual globin molecule (␣-or ␤-chain) is capable of cotranslational heme binding. For the in vitro translation in a wheat germ system we chose the ␣-globin that has a 10-fold stronger ability to bind the heme group as compared with the ␤-globin (30,39) and, in contrast to ␤-globin, does not form the tetramer structure (31). approximately 100 amino acid residues and longer were capable of binding the heme (29).…”

Section: Full-length ␣-Globin Is Capable Of Cotranslational Hemementioning

confidence: 99%

“…Then the nascent ribosome-bound globin peptide of 86 amino acid residues should be able to bind hemin either without F helix, if just 15 amino acid residues are hidden (41, 42), or without both E and F helices, if 30 -40 amino acids are accommodated within the ribosome (39,42,44). The latter seems unlikely.…”

Section: Shorter ␣-Globin Peptides Of 75 65 and 34 Amino Acid Residmentioning

confidence: 99%

Cotranslational Folding of Globin

Komar

Kommer

Krasheninnikov

et al. 1997

Journal of Biological Chemistry

142

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Globin synthesis in a wheat germ cell-free translation system was performed in the presence of [ 3 H]hemin and [ 35 S]methionine to determine the minimal length of the nascent ribosome-bound globin chain capable of heme binding. Nascent polypeptides of predetermined size were synthesized on ribosomes by translation of truncated mRNA molecules. Analysis with the use of sucrose gradient centrifugation and puromycin reaction revealed that the ribosome-bound N-terminal ␣-globin fragments of 140, 100, and 86 amino acid residues are capable of an efficient heme binding, whereas those of 75, 65, and 34 amino acid residues display a significantly weaker, or just nonspecific, affinity to heme. This indicates that the ribosome-bound nascent chain of 86 amino acid residues has already acquired a spatial structure that allows its interaction with the heme group or that heme attachment promotes the formation of the proper tertiary structure in the ribosome-bound nascent peptide. In any case the cotranslational folding of globin is suggested.

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Distribution of heme in systems containing heme-free and heme-bound hemoglobin chains

Cited by 23 publications

References 19 publications

Mechanism governing heme synthesis reveals a GATA factor/heme circuit that controls differentiation

Mechanism governing heme synthesis reveals a GATA factor/heme circuit that controls differentiation

The Role of Alpha-Hemoglobin Stabilizing Protein in Redox Chemistry, Denaturation, and Hemoglobin Assembly

Cotranslational Folding of Globin

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