The
            <i>Arabidopsis thaliana HY1</i>
            locus, required for phytochrome-chromophore biosynthesis, encodes a protein related to heme oxygenases

Davis, Seth J; Kurepa, Jasmina; Vierstra, Richard D.

doi:10.1073/pnas.96.11.6541

Cited by 224 publications

(169 citation statements)

References 58 publications

(76 reference statements)

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“…A G-to-A change was found in the HO1 (HY1) gene, which led to a change of amino acid 265 from Glu to Lys. Glu-265 has been shown to be highly conserved in heme oxygenases from Arabidopsis, cyanobacteria, algae, and animals (30). We named this line hy1-201.…”

Section: Intragenic Phyb Mutationsmentioning

confidence: 99%

Characterization of the requirements for localization of phytochrome B to nuclear bodies

Meng

Schwab

Chory

2003

Proc. Natl. Acad. Sci. U.S.A.

160

213

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Phytochromes are red-and far-red-sensing photoreceptors that detect the quantity, quality, and duration of light throughout the entire life cycle of plants. Phytochromes accumulate in the cytoplasm in the dark. As one of the earliest responses after light illumination, phytochromes localize to the nucleus where they become associated with discrete nuclear bodies (NBs). Here, we describe the steady-state dynamics of Arabidopsis phytochrome B (phyB) localization in response to different light conditions and define four phyB subnuclear localization patterns: diffuse nuclear localization, small and numerous NBs only, both small and large NBs, and large NBs only. We show that phyB nuclear import is not sufficient for phyB NB formation. Rather, phyB accumulation in NBs is mainly determined by the percentage of the total amount of phyB protein that is in the active phyB conformer, with large NBs always correlating with strong phyB responses. A genetic screen to identify determinants required for subnuclear localization of phyB resulted in several phyB mutants, mutants deficient in phytochrome chromophore biosynthesis, and mutations in at least one previously uninvestigated locus. This study lays the groundwork for future investigations to identify the molecular mechanisms of light-regulated partitioning of plant photoreceptors to discrete subnuclear domains.

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Section: Intragenic Phyb Mutationsmentioning

confidence: 99%

Characterization of the requirements for localization of phytochrome B to nuclear bodies

Meng

Schwab

Chory

2003

Proc. Natl. Acad. Sci. U.S.A.

160

213

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“…Heme is cleaved to BV by a ferredoxin-dependent heme oxygenase, and then further reduced by a family of bilin reductases. The gene for heme oxygenase from higher plants was first identified by positional cloning of the Arabidopsis HY1 gene [3,4] and subsequently an enzymatic assay was performed with recombinant HY1 protein [4,5]. A cyanobacterial gene for heme oxygenase (ho1) from Synechocystis PCC6803 was also identified by genetic complementation of the Arabidopsis hy1 mutant [6].…”

Section: Introductionmentioning

confidence: 99%

Metabolic engineering to produce phytochromes with phytochromobilin, phycocyanobilin, or phycoerythrobilin chromophore in Escherichia coli

et al. 2006

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By co-expression of heme oxygenase and various bilin reductase(s) in a single operon in conjunction with apophytochrome using two compatible plasmids, we developed a system to produce phytochromes with various chromophores in Escherichia coli. Through the selection of different bilin reductases, apophytochromes were assembled with phytochromobilin, phycocyanobilin, and phycoerythrobilin. The blue-shifted difference spectra of truncated phytochromes were observed with a phycocyanobilin chromophore compared to a phytochromobilin chromophore. When the phycoerythrobilin biosynthetic enzymes were co-expressed, E. coli cells accumulated orange-fluorescent phytochrome. The metabolic engineering of bacteria for the production of various bilins for assembly into phytochromes will facilitate the molecular analysis of photoreceptors.

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“…1). HO has been identified in a wide array of organisms, including mammals (1, 2), insects (3,4), and photosynthetic organisms (5,6). Of particular interest, HO is present in many pathogenic bacteria (7)(8)(9)(10), including Neisseria meningitidis (11) and Pseudomonas aeruginosa (12).…”

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confidence: 99%

Diatomic Ligand Discrimination by the Heme Oxygenases from Neisseria meningitidis and Pseudomonas aeruginosa

Friedman

Meharenna

Wilks

et al. 2007

Journal of Biological Chemistry

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Heme oxygenases have an increased binding affinity for O 2 relative to CO. Such discrimination is critical to the function of HO enzymes because one of the main products of heme catabolism is CO. Kinetic studies of mammalian and bacterial HO proteins reveal a significant decrease in the dissociation rate of O 2 relative to other heme proteins such as myoglobin. Here we report the kinetic rate constants for the binding of O 2 and CO by the heme oxygenases from Neisseria meningitidis (nmHO) and Pseudomonas aeruginosa (paHO). A combination of stoppedflow kinetic and laser flash photolysis experiments reveal that nmHO and paHO both maintain a similar degree of ligand discrimination as mammalian HO-1 and the HO from Corynebacterium diphtheriae. However, in addition to the observed decrease in dissociation rate for O 2 by both nmHO and paHO, kinetic analyses show an increase in dissociation rate for CO by these two enzymes. The crystal structures of nmHO and paHO both contain significant differences from the mammalian HO-1 and bacterial C. diphtheriae HO structures, which suggests a structural basis for ligand discrimination in nmHO and paHO. Heme oxygenase (HO)2 catalyzes the oxidative degradation of heme to biliverdin, iron, and CO (Fig. 1). HO has been identified in a wide array of organisms, including mammals (1, 2), insects (3, 4), and photosynthetic organisms (5, 6). Of particular interest, HO is present in many pathogenic bacteria (7-10), including Neisseria meningitidis (11) and Pseudomonas aeruginosa (12). These pathogenic bacteria have developed sophisticated heme uptake systems that harness the iron from hemecontaining proteins present in the host (13-15). The HO enzymes from N. meningitidis (nmHO) and P. aeruginosa (paHO) are both essential for the utilization of iron from imported heme, and the crystal structures of these two bacterial HO enzymes have now been solved (16,17). Although most HOs hydroxylate exclusively the ␣-meso heme carbon (Fig. 1), paHO is unusual because the ␥-meso carbon is the predominate site of hydroxylation (18) even though the structure paHO is very much the same as other HOs. The difference in hydroxylation patterns is due to an ϳ100 o rotation of the heme in paHO relative to other HOs which places the ␥-meso carbon at the same position in the active site as the ␣-meso carbon in other HOs (16).The Fe(II) atom of the heme prosthetic group of heme proteins is an efficient binder of O 2 , NO, and CO, and the binding by heme proteins of these diatomic molecules is of critical importance to physiological processes such as respiration, vasodilation, and neurotransmission (19 -21). A common feature shared by all heme proteins is the need to not only bind its target ligand but also to discriminate against the binding of heme ligands of similar size and shape. Fe(II) adducts of CO are normally linear because backbonding is optimized by the overlap of Fe(II) d-orbitals with the empty * orbitals of . In contrast, Fe(II)-NO and Fe(II)-O 2 are naturally bent in order to maximize overlap with ...

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The Arabidopsis thaliana HY1 locus, required for phytochrome-chromophore biosynthesis, encodes a protein related to heme oxygenases

Cited by 224 publications

References 58 publications

Characterization of the requirements for localization of phytochrome B to nuclear bodies

Characterization of the requirements for localization of phytochrome B to nuclear bodies

Metabolic engineering to produce phytochromes with phytochromobilin, phycocyanobilin, or phycoerythrobilin chromophore in Escherichia coli

Diatomic Ligand Discrimination by the Heme Oxygenases from Neisseria meningitidis and Pseudomonas aeruginosa

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