Nonvertebrate hemoglobins: Structural bases for reactivity

Bolognesi, Martino; Bordo, Domenico; Rizzi, Menico; Tarricone, C.; Ascenzi, Paolo

doi:10.1016/s0079-6107(97)00017-5

Cited by 173 publications

(205 citation statements)

References 176 publications

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“…Hemoglobins (Hbs) are ubiquitous proteins found in bacteria, fungi, plants, protozoa, and animals (Vinogradov et al 1993, Bolognesi et al 1997. Plants contain two types of Hbs: the symbiotic and nonsymbiotic (ns) Hbs (Appleby 1992, Andersson et at.…”

Section: Introductionmentioning

confidence: 99%

Nonsymbiotic hemoglobins in rice are synthesized during germination and in differentiating cell types

et al. 2001

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Shearman, L.; Mathiesen, M.; Zhou, Y.J.; Arredondo-Peter, R.; Sarath, Gautam; and Klucas, R. V., "Nonsymbiotic hemoglobins in rice are synthesized during germination and in differentiating cell types" (2001 Abstract: Nonsymbiotic hemoglobins (ns-Hbs) previously have been found in monocots and dicots; however, very little is known about the tissue and cell type localization as well as the physiological function(s) of these oxygen-binding proteins. We report the immunodetection and immunolocalization of ns-Hbs in rice (Oryza sativa L.) by Western blotting and in situ confocal laser scanning techniques. Ns-Hbs were detected in soluble extracts of different tissues from the developing rice seedling by immunoblotting. Levels of ns-Hbs increased in the germinating seed for the fi rst six days following imbibition and remained relatively constant thereafter. In contrast, ns-Hb levels decreased during leaf maturation. Roots and mesocotyls contained detectable, but low levels of ns-Hbs. Split-seed experiments revealed that ns-Hbs are synthesized de novo during seed germination and are expressed in the absence of any signal originating from the embryo. Immunolocalization of ns-Hbs by con-focal microscopy indicated the presence of ns-Hbs primarily in differentiated and differentiating cell types of the developing seedling, such as the aleurone, scutellum, root cap cells, sclerenchyma, and tracheary elements. To our knowledge, this is the fi rst report of the specifi c cellular localization of these proteins during seedling development.

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Section: Introductionmentioning

confidence: 99%

Nonsymbiotic hemoglobins in rice are synthesized during germination and in differentiating cell types

et al. 2001

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“…On the other hand, the ferrous form of the protein shows substantial stability over a wide pH range. These observations suggest that Scapharca hemoglobin has a unique heme structure that undergoes substantial redox-dependent rearrangements that stabilize the Fe-proximal histidine bond in the functional deoxy form of the protein but not in the ferric form.The homodimeric hemoglobin (HbI) 1 isolated from arcid clam Scapharca inaequivalvis possesses unique structural features (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Although HbI has a low sequence homology with tetrameric mammalian hemoglobins (Hb), it has a conserved globin fold.…”

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confidence: 99%

Hydroxide Rather Than Histidine Is Coordinated to the Heme in Five-coordinate Ferric Scapharca inaequivalvisHemoglobin

Das¹,

Boffi²,

Chiancone³

et al. 1999

Journal of Biological Chemistry

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The ferric form of the homodimeric Scapharca hemoglobin undergoes a pH-dependent spin transition of the heme iron. The transition can also be modulated by the presence of salt. From our earlier studies it was shown that three distinct species are populated in the pH range 6 -9. At acidic pH, a low-spin six-coordinate structure predominates. At neutral and at alkaline pHs, in addition to a small population of a hexacoordinate high-spin species, a pentacoordinate species is significantly populated. Isotope difference spectra clearly show that the heme group in the latter species has a hydroxide ligand and thereby is not coordinated by the proximal histidine. The stretching frequency of the Fe-OH moiety is 578 cm ؊1 and shifts to 553 cm ؊1 in H 2 18 O, as would be expected for a Fe-OH unit. On the other hand, the ferrous form of the protein shows substantial stability over a wide pH range. These observations suggest that Scapharca hemoglobin has a unique heme structure that undergoes substantial redox-dependent rearrangements that stabilize the Fe-proximal histidine bond in the functional deoxy form of the protein but not in the ferric form.The homodimeric hemoglobin (HbI) 1 isolated from arcid clam Scapharca inaequivalvis possesses unique structural features (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Although HbI has a low sequence homology with tetrameric mammalian hemoglobins (Hb), it has a conserved globin fold. It displays a unique structural basis for cooperative ligand binding in that the two hemes face each other across the intersubunit contact and are able to communicate directly through their propionate groups (2,4,15,16). As a consequence of this unusual structural linkage, cooperativity is accompanied by major tertiary changes in the heme environment with only minor rearrangements of the quaternary structure, in contrast to mammalian Hbs (2, 13). The subunit interface in HbI is formed mostly by the helices E and F, which are solventexposed in tetrameric mammalian Hbs.Although a wealth of structural and functional information is available on the ferrous deoxy and ligand-bound forms of HbI (2-14), little is known about the oxidized form (1). The heme structure in the ferric form undergoes a spin transition that is dependent on pH and salt concentration (17,18). From our earlier studies by optical and resonance Raman spectroscopy, it was shown that a mixture of three distinct species are populated in the pH range 6 -9 (17, 18). The formation of a sixcoordinate low-spin heme is favored at acidic pH and high ionic strength and is accompanied by the reversible dissociation of the HbI dimer into monomers. This species is likely to be formed by coordination of the distal histidine to the heme (in addition to the proximal histidine) as shown by EPR studies (18). At neutral pH values, a dimeric pentacoordinate species appears and becomes the dominant form at alkaline pH and low salt. A population of dimeric six-coordinate high-spin heme exists over the entire 6 -9 pH-range and in both low and high salt. Thi...

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“…The Rp-NP1:histamine complex is stabilized by hydrogen bonds that occur between the Asp30 and Glu32 residues of Rp-NP1 and the alkylammonium group of histamine ( Figure 2) (23). This possibly reflects the different proximal His-heme-Fe geometry of all-α and all-β heme-proteins (7,58).…”

Section: Rhodnius Prolixus Nitrophorinsmentioning

confidence: 99%

“…They perform a wide range of essential biological functions including ligand transport, storage and sensing, as well as heme-Fe-based catalysis (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12).…”

Section: Introductionmentioning

confidence: 99%

“…The other axial position faces the so-called 'distal' E7 residue, which was demonstrated to contribute substantially to the stability of the heme-bound ligand and to the reversibility of the reaction. Of note, the occurrence of a His residue at the E7 position may lead to hexa-coordination of the heme Fe-atom impairing ligand binding ( Figure 1) (2,7,12,(21)(22)(23)(24).…”

Section: Introductionmentioning

confidence: 99%

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Nitrophorins and nitrobindins: structure and function

Ascenzi

Masi

et al. 2017

Biomolecular Concepts

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Classical all α-helical globins are present in all living organisms and are ordered in three lineages: (i) flavohemoglobins and single domain globins, (ii) protoglobins and globin coupled sensors and (iii) truncated hemoglobins, displaying the 3/3 or the 2/2 all α-helical fold. However, over the last two decades, all β-barrel and mixed α-helical-β-barrel heme-proteins displaying hemebased functional properties (e.g. ligand binding, transport and sensing) closely similar to those of all α-helical globins have been reported. Monomeric nitrophorins (NPs) and α 1 -microglobulin (α 1 -m), belonging to the lipocalin superfamily and nitrobindins (Nbs) represent prototypical heme-proteins displaying the all β-barrel and mixed α-helical-β-barrel folds. NPs are confined to the Reduviidae and Cimicidae families of Heteroptera, whereas α 1 -m and Nbs constitute heme-protein families spanning bacteria to Homo sapiens. The structural organization and the reactivity of the stable ferric solvent-exposed heme-Fe atom suggest that NPs and Nbs are devoted to NO transport, storage and sensing, whereas Hs-α 1 -m participates in heme metabolism. Here, the structural and functional properties of NPs and Nbs are reviewed in parallel with those of sperm whale myoglobin, which is generally taken as the prototype of monomeric globins.

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Nonvertebrate hemoglobins: Structural bases for reactivity

Cited by 173 publications

References 176 publications

Nonsymbiotic hemoglobins in rice are synthesized during germination and in differentiating cell types

Nonsymbiotic hemoglobins in rice are synthesized during germination and in differentiating cell types

Hydroxide Rather Than Histidine Is Coordinated to the Heme in Five-coordinate Ferric Scapharca inaequivalvisHemoglobin

Nitrophorins and nitrobindins: structure and function

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