The Globins of Cyanobacteria and Algae

Johnson, Eric A.; Lecomte, Juliette T. J.

doi:10.1016/b978-0-12-407693-8.00006-6

Cited by 17 publications

(13 citation statements)

References 176 publications

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“…To our knowledge, PhTAC125 is the first example of coexistence of genes encoding a FHb and three 2/2Hbs (Giordano et al, 2013), of which both Ph-2/2HbO-0030 and Ph-2/2HbO-2217 are endowed with hexa-coordination (Giordano et al, 2011;Howes et al, 2011;Russo et al, 2013;Giordano et al, 2015;this study). Endogenous hexacoordination may be essential for proteins that function under high levels of oxidative stress (Johnson and Lecomte, 2013).…”

Section: Discussionmentioning

confidence: 99%

Coexistence of multiple globin genes conferring protection against nitrosative stress to the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125

et al. 2018

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Despite the large number of globins recently discovered in bacteria, our knowledge of their physiological functions is restricted to only a few examples. In the microbial world, globins appear to perform multiple roles in addition to the reversible binding of oxygen; all these functions are attributable to the heme pocket that dominates functional properties. Resistance to nitrosative stress and involvement in oxygen chemistry seem to be the most prevalent functions for bacterial globins, although the number of globins for which functional roles have been studied via mutation and genetic complementation is very limited. The acquisition of structural information has considerably outpaced the physiological and molecular characterisation of these proteins. The genome of the Antarctic cold-adapted bacterium Pseudoalteromonas haloplanktis TAC125 (PhTAC125) contains genes encoding three distinct single-chain 2/2 globins, supporting the hypothesis of their crucial involvement in a number of functions, including protection against oxidative and nitrosative stress in the cold and O-rich environment. In the genome of PhTAC125, the genes encoding 2/2 globins are constitutively transcribed, thus suggesting that these globins are not functionally redundant in their physiological function in PhTAC125. In the present study, the physiological role of one of the 2/2 globins, Ph-2/2HbO-2217, was investigated by integrating in vivo and in vitro results. This role includes the involvement in the detoxification of reactive nitrogen and O species including NO by developing two in vivo and in vitro models to highlight the protective role of Ph-2/2HbO-2217 against reactive nitrogen species. The PSHAa2217 gene was cloned and over-expressed in the flavohemoglobin-deficient mutant of Escherichia coli and the growth properties and O uptake in the presence of NO of the mutant carrying the PSHAa2217 gene were analysed. The ferric form of Ph-2/2HbO-2217 is able to catalyse peroxynitrite isomerisation in vitro, indicating its potential role in the scavenging of reactive nitrogen species. Here we present in vitro evidence for the detoxification of NO by Ph-2/2HbO-2217.

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Section: Discussionmentioning

confidence: 99%

Coexistence of multiple globin genes conferring protection against nitrosative stress to the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125

et al. 2018

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“…The GlbN protein (‘cyanoglobin’) is shorter (‘truncated’) than vertebrate Glbs but similar in length to protozoan Glbs. The GlbNs of two non‐nitrogen fixing cyanobacteria, Synechocystis PCC 6803 and Synechococcus PCC 7002, are also truncated and hexacoordinate, having His residues as proximal and distal heme ligands (Hoy et al , ; Johnson & Lecomte, ). In addition, both GlbNs display a rare feature: they have a non‐axial His covalently bound to a heme vinyl group, which prevents heme dissociation in both ferric and ferrous forms (Hoy et al , ; Scott et al , ).…”

Section: Globins Of Cyanobacteria and Algaementioning

confidence: 99%

“…The Glbs of green algae (chlorophytes) belong to the TrHb1, TrHb2 and single‐domain subfamilies according to a comprehensive genome mining study of microbial eukaryotes (Johnson & Lecomte, ; Vinogradov et al , ). The discovery and characterization of algal Glbs shortly followed those of cyanoglobin (Johnson & Lecomte, ).…”

Section: Globins Of Cyanobacteria and Algaementioning

confidence: 99%

Plant hemoglobins: a journey from unicellular green algae to vascular plants

et al. 2020

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Globins (Glbs) are widely distributed in archaea, bacteria and eukaryotes. They can be classified into proteins with 2/2 or 3/3 a-helical folding around the heme cavity. Both types of Glbs occur in green algae, bryophytes and vascular plants. The Glbs of angiosperms have been more intensively studied, and several protein structures have been solved. They can be hexacoordinate or pentacoordinate, depending on whether a histidine is coordinating or not at the sixth position of the iron atom. The 3/3 Glbs of class 1 and the 2/2 Glbs (also called class 3 in plants) are present in all angiosperms, whereas the 3/3 Glbs of class 2 have been only found in early angiosperms and eudicots. The three Glb classes are expected to play different roles. Class 1 Glbs are involved in hypoxia responses and modulate NO concentration, which may explain their roles in plant morphogenesis, hormone signaling, cell fate determination, nutrient deficiency, nitrogen metabolism and plant-microorganism symbioses. Symbiotic Glbs derive from class 1 or class 2 Glbs and transport O 2 in nodules. The physiological roles of class 2 and class 3 Glbs are poorly defined but could involve O 2 and NO transport and/or metabolism, respectively. More research is warranted on these intriguing proteins to determine their non-redundant functions.

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“…20 In fact, it has been difficult to obtain biological information in part because these globins occur at relatively low levels and are generally not essential under most growth conditions. THB1 offers a rare opportunity to explore the properties of a TrHb and connect in vitro and in vivo information in a model organism.…”

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Characterization of THB1, a Chlamydomonas reinhardtii Truncated Hemoglobin: Linkage to Nitrogen Metabolism and Identification of Lysine as the Distal Heme Ligand

et al. 2014

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The nuclear genome of the model organism Chlamydomonas reinhardtii contains genes for a dozen hemoglobins of the truncated lineage. Of those, THB1 is known to be expressed, but the product and its function have not yet been characterized. We present mutagenesis, optical, and nuclear magnetic resonance data for the recombinant protein and show that at pH near neutral in the absence of added ligand, THB1 coordinates the heme iron with the canonical proximal histidine and a distal lysine. In the cyanomet state, THB1 is structurally similar to other known truncated hemoglobins, particularly the heme domain of Chlamydomonas eugametos LI637, a light-induced chloroplastic hemoglobin. Recombinant THB1 is capable of binding nitric oxide (NO•) in either the ferric or ferrous state and has efficient NO• dioxygenase activity. By using different C. reinhardtii strains and growth conditions, we demonstrate that the expression of THB1 is under the control of the NIT2 regulatory gene and that the hemoglobin is linked to the nitrogen assimilation pathway.

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The Globins of Cyanobacteria and Algae

Cited by 17 publications

References 176 publications

Coexistence of multiple globin genes conferring protection against nitrosative stress to the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125

Coexistence of multiple globin genes conferring protection against nitrosative stress to the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125

Plant hemoglobins: a journey from unicellular green algae to vascular plants

Characterization of THB1, a Chlamydomonas reinhardtii Truncated Hemoglobin: Linkage to Nitrogen Metabolism and Identification of Lysine as the Distal Heme Ligand

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