The Structure of Deoxy- and Oxy-leghaemoglobin from Lupin

Harutyunyan, Hasmik; Safonova, T. N.; Куранова, И. П.; Попов, А. Н.; Teplyakov, A.; Obmolova, Galina; Rusakov, A. A.; Vaĭnshteĭn, B. K.; Dodson, Guy; Wilson, Julie; Perutz, M. F.

doi:10.1006/jmbi.1995.0419

Cited by 77 publications

(59 citation statements)

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“…The fact that Lb has a larger distal heme cavity than Mb has been reported previously for both soybean Lb a (Ollis et al, 1983) and lupin Lb II (Arutyunyan, Kuranova, Vainshtein & Steigemann, 1980;Arutyunyan, Kuranova, Tovbis et al, 1980;Harutyunyan et al, 1995). B, C, E, G and H helices all align closely.…”

Section: The Heme Group and Heme Cavitysupporting

confidence: 65%

“…Lb a from soybean (Glycine max), while most of the X-ray crystallographic studies have centered on Lb II from yellow lupin (Lupinus luteus) (see, for example, Narula, Dalvit, Appleby & Wright, 1988;Harutyunyan et al, 1995). The soybean and lupin proteins are distant on the phylogenetic tree (Andersson, Jensen, Llewellyn, Dennis & Peacock, 1997), and differ significantly in length: soybean Lb a has 143 residues while lupin Lb II has 153 residues.…”

Section: Introductionmentioning

confidence: 99%

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Structure of Ferric Soybean LeghemoglobinaNicotinate at 2.3 Å Resolution

Ellis¹,

Appleby²,

Guss³

et al. 1997

Acta Cryst D

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Soybean leghemoglobin a is a small (16 kDa) protein facilitating the transport of Oz to respiring N2-fixing bacteria at low free-O2 tension. The crystal structure of soybean ferric leghemoglobin a nicotinate has been refined at 2.3 A resolution. The final R factor is 15.8% for 6877 reflections between 6.0 and 2.3 ~. The structure of soybean leghemoglobin a (143 residues) is closely similar to that of lupin leghemoglobin II (153 residues), the proteins having 82 identical residues when the sequences are aligned. The new structure provides support for the conclusion that the unique properties of leghemoglobin arise principally from a heme pocket considerably larger and more flexible than that of myoglobin, a strongly ruffled heme group, and a proximal histidine orientation more favourable to ligand binding.

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Section: The Heme Group and Heme Cavitysupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Structure of Ferric Soybean LeghemoglobinaNicotinate at 2.3 Å Resolution

Ellis¹,

Appleby²,

Guss³

et al. 1997

Acta Cryst D

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“…reported for mammalian Mbs and are not observed for either BjFixL or R220A BjFixL, but they are evident from NMR and even X-ray spectroscopic analyses of Lb (25)(26)(27). We therefore propose that the rotational freedom of the proximalhistidine imidazole, rather than the initial position of that imidazole, is a better determinant of the intrinsic reactivity of the iron atom in heme proteins.…”

Section: A Heme Iron Intrinsically Unreactive Toward Binding Of Omentioning

confidence: 72%

A Distal Arginine in Oxygen-Sensing Heme-PAS Domains Is Essential to Ligand Binding, Signal Transduction, and Structure

et al. 2003

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To evaluate the contributions of the Gβ-2 arginine to signal transduction in oxygen-sensing heme-PAS domains, we replaced this residue with alanine in Bradyrhizobium japonicum FixL and examined the results on heme-domain structure, ligand binding, and kinase regulation. In the isolated R220A BjFixL heme-PAS domain, the iron−histidine bond was increased in length by 0.31 Å, the heme flattened even without a ligand, and the interaction of a presumed regulatory loop (the FG loop) with the helix of heme attachment was weakened. Binding of carbon monoxide was similar for ferrous BjFixL and R220A BjFixL. In contrast, the level of binding of oxygen was dramatically lower (K d ∼ 1.5 mM) for R220A BjFixL, and this was manifested as 60- and 3-fold lower on- and off-rate constants, respectively. Binding of cyanide followed the same pattern as binding of oxygen. The catalytic activity was 3−4-fold higher in the “on-state” unliganded forms of R220A BjFixL than in the corresponding BjFixL species. Cyanide regulation of this activity was strongly impaired, but some inhibition was nevertheless preserved. Carbon monoxide and nitric oxide regulation, although weak in BjFixL, were abolished from R220A BjFixL. We conclude that the Gβ-2 arginine assists in the binding of oxygen to BjFixL but does not accomplish this by stabilizing the oxy form. This arginine is not absolutely required for regulation, although it is important for shifting a pre-existing kinase equilibrium toward the inactive state on binding of regulatory ligands. These findings support a regulatory model in which the heme-PAS domain operates as an ensemble that couples to the kinase rather than a mechanism driven by a single central switch.

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“…leghemoglobin (51,52) or Ascaris Hb (53). The imidazole plane of the proximal His side chain is in-line with the meso ␤-␦ carbon axis of the porphyrin ring, as in the ferrous ligand-free heme-HmuO complex (14).…”

Section: Resultsmentioning

confidence: 98%

Crystal Structure of the Dioxygen-bound Heme Oxygenase from Corynebacterium diphtheriae

Unno

Matsui

Chu

et al. 2004

Journal of Biological Chemistry

100

171

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HmuO, a heme oxygenase of Corynebacterium diphtheriae, catalyzes degradation of heme using the same mechanism as the mammalian enzyme. The oxy form of HmuO, the precursor of the catalytically active ferric hydroperoxo species, has been characterized by ligand binding kinetics, resonance Raman spectroscopy, and x-ray crystallography. The oxygen association and dissociation rate constants are 5 M ؊1 s ؊1 and 0.22 s ؊1 , respectively, yielding an O 2 affinity of 21 M ؊1 , which is ϳ20 times greater than that of mammalian myoglobins. However, the affinity of HmuO for CO is only 3-4-fold greater than that for mammalian myoglobins, implying the presence of strong hydrogen bonding interactions in the distal pocket of

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The Structure of Deoxy- and Oxy-leghaemoglobin from Lupin

Cited by 77 publications

References 0 publications

Structure of Ferric Soybean LeghemoglobinaNicotinate at 2.3 Å Resolution

Structure of Ferric Soybean LeghemoglobinaNicotinate at 2.3 Å Resolution

A Distal Arginine in Oxygen-Sensing Heme-PAS Domains Is Essential to Ligand Binding, Signal Transduction, and Structure

Crystal Structure of the Dioxygen-bound Heme Oxygenase from Corynebacterium diphtheriae

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