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Globin-like proteins in caenorhabditis elegans: in vivo localization, ligand binding and structural properties


Geuens, E; Hoogewijs, D; Nardini, M; Vinck, E; Pesce, A; Kiger, L; Fago, A; Tilleman, L; De Henau, S; Marden, M C; Weber, R E; Van Doorslaer, S; Vanfleteren, J; Moens, L; Bolognesi, M; Dewilde, S (2010). Globin-like proteins in caenorhabditis elegans: in vivo localization, ligand binding and structural properties. BMC Biochemistry, 11:17.

Abstract

Abstract
Background: The genome of the nematode Caenorhabditis elegans contains more than 30 putative globin genes that
all are transcribed. Although their translated amino acid sequences fit the globin fold, a variety of amino-acid
substitutions and extensions generate a wide structural diversity among the putative globins. No information is
available on the physicochemical properties and the in vivo expression.
Results: We expressed the globins in a bacterial system, characterized the purified proteins by optical and resonance
Raman spectroscopy, measured the kinetics and equilibria of O2 binding and determined the crystal structure of GLB-
1* (CysGH2 T Ser mutant). Furthermore, we studied the expression patterns of glb-1 (ZK637.13) and glb-26 (T22C1.2) in
the worms using green fluorescent protein technology and measured alterations of their transcript abundances under
hypoxic conditions.GLB-1* displays the classical three-over-three α-helical sandwich of vertebrate globins, assembled
in a homodimer associated through facing E- and F-helices. Within the heme pocket the dioxygen molecule is
stabilized by a hydrogen bonded network including TyrB10 and GlnE7.GLB-1 exhibits high ligand affinity, which is,
however, lower than in other globins with the same distal TyrB10-GlnE7 amino-acid pair. In the absence of external
ligands, the heme ferrous iron of GLB-26 is strongly hexacoordinated with HisE7, which could explain its extremely low
affinity for CO. This globin oxidizes instantly to the ferric form in the presence of oxygen and is therefore incapable of
reversible oxygen binding.
Conclusion: The presented data indicate that GLB-1 and GLB-26 belong to two functionally-different globin classes.

Abstract
Background: The genome of the nematode Caenorhabditis elegans contains more than 30 putative globin genes that
all are transcribed. Although their translated amino acid sequences fit the globin fold, a variety of amino-acid
substitutions and extensions generate a wide structural diversity among the putative globins. No information is
available on the physicochemical properties and the in vivo expression.
Results: We expressed the globins in a bacterial system, characterized the purified proteins by optical and resonance
Raman spectroscopy, measured the kinetics and equilibria of O2 binding and determined the crystal structure of GLB-
1* (CysGH2 T Ser mutant). Furthermore, we studied the expression patterns of glb-1 (ZK637.13) and glb-26 (T22C1.2) in
the worms using green fluorescent protein technology and measured alterations of their transcript abundances under
hypoxic conditions.GLB-1* displays the classical three-over-three α-helical sandwich of vertebrate globins, assembled
in a homodimer associated through facing E- and F-helices. Within the heme pocket the dioxygen molecule is
stabilized by a hydrogen bonded network including TyrB10 and GlnE7.GLB-1 exhibits high ligand affinity, which is,
however, lower than in other globins with the same distal TyrB10-GlnE7 amino-acid pair. In the absence of external
ligands, the heme ferrous iron of GLB-26 is strongly hexacoordinated with HisE7, which could explain its extremely low
affinity for CO. This globin oxidizes instantly to the ferric form in the presence of oxygen and is therefore incapable of
reversible oxygen binding.
Conclusion: The presented data indicate that GLB-1 and GLB-26 belong to two functionally-different globin classes.

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11 citations in Web of Science®
12 citations in Scopus®
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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Center for Integrative Human Physiology
04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2 April 2010
Deposited On:19 May 2010 08:13
Last Modified:05 Apr 2016 14:08
Publisher:BioMed Central
ISSN:1471-2091
Funders:Fund for Scientific research (FWO), BOF UA TOP 2006, Danish Natural Science Research Council, Novo Nordisk, Lunbeck and Carlsberg-Foundations, Italian Ministry of University and Scientific Research and University of Milano, Inserm and the Univ. Paris 11
Publisher DOI:https://doi.org/10.1186/1471-2091-11-17
Permanent URL: https://doi.org/10.5167/uzh-34110

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