Overexpression of class 1 plant hemoglobin genes enhances symbiotic nitrogen fixation activity between <i>Mesorhizobium loti</i> and <i>Lotus japonicus</i>

Shimoda, Yoshikazu; Shimoda-Sasakura, Fuyuko; Kucho, Ken-ichi; Kanamori, Norihito; Nagata, Masaki; Suzuki, Akihiro; Abe, Mikiko; Higashi, Shiro; Uchiumi, Toshiki

doi:10.1111/j.1365-313x.2008.03689.x

Cited by 92 publications

(101 citation statements)

References 40 publications

(69 reference statements)

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“…One way to stabilize the oxygen level in a suitable range in the nodules is to express a large amount (up to 30% of nodular proteins) of leghemeglobin (2), a hemecontaining, oxygen-binding protein (33). Overexpression of leghemoglobin was shown to enhance the symbiotic nitrogen fixing activity between M. loti and Lotus japonicus (45). B. japonicum can also synthesize heme (13) and export the heme to periplasm by the cycVWX complex for cytochrome c biogenesis (14,39).…”

Section: Involvement Of Tbdrs In the Iron Uptake Mechanism Of Rhizobamentioning

confidence: 99%

TonB-Dependent Receptors in Nitrogen-Fixing Nodulating Bacteria

Lim

2010

Microb. Environ.

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TonB-dependent receptors (TBDRs) allow Gram-negative bacteria to uptake scarce resources from competitive environments with very high affinity. Early reports on TBDRs focused on the uptake of siderophore-iron complexes but recent studies have showed that the spectrum of ligands includes sugars, vitamins, heme, and other non-ferrous cations. To investigate the possible roles of TBDRs in nitrogen-fixing, nodulating bacteria, a bioinformatics approach was adopted to identify their presence in the genome of 13 selected rhizobacteria. The number of TBDR-like genes ranged from 1 (Mesorhizobium loti MAFF303099) to 14 (Azorhizobium caulinodans ORS 571 and Methylobacterium nodulans ORS 2060). These TBDRs can be largely grouped into two clusters, the 'heme' cluster and the 'ironsiderophores' cluster. The only exceptions are a putative nickel-specific TBDR (bll6948) in Bradyrhizobium japonicum USDA110 and two putative sugar-specific TBDRs in B. japonicum USDA110 and A. caulinodans ORS571 genomes, respectively. No TBDR-like sequences lie in the 'Vitamin B12' or 'Non-Fe cations' clusters. A model of the biological roles of TBDRs in free-living and symbiotic states is proposed for B. japonicum.

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Section: Involvement Of Tbdrs In the Iron Uptake Mechanism Of Rhizobamentioning

confidence: 99%

TonB-Dependent Receptors in Nitrogen-Fixing Nodulating Bacteria

Lim

2010

Microb. Environ.

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“…The involvement of NO in nitrogenase inactivation has been demonstrated in soybean (Glycine max) and Lotus after nitrate supply (Kanayama et al, 1990;Meakin et al, 2007;Kato et al, 2010). In Lotus japonicus, the artificial application of the NO donor sodium nitroprusside (SNP) decreased nitrogen fixation, whereas the application of a NO scavenger (2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) enhanced nitrogen fixation (Shimoda et al, 2009;Kato et al, 2010). In spite of the inhibitory effect of NO on nitrogenase, it appears that NO production is required for nodule development and functioning, and the plant antioxidant systems appear to be crucial to maintain nodule functioning Keyster et al, 2010;Leach et al, 2010;Sanchez et al, 2011).…”

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confidence: 99%

“…Nitroso-leghemoglobin complexes have been detected in nodules of soybean and Lotus (Kanayama et al, 1990;Mathieu et al, 1998;Meakin et al, 2007;Sanchez et al, 2010). This NO-scavenging function has also been attributed to nonsymbiotic hemoglobins in L. japonicus, which are induced upon symbiotic infection and accumulate in nitrogen-fixing nodules (Shimoda et al, 2009).…”

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confidence: 99%

Glutamine Synthetase Is a Molecular Target of Nitric Oxide in Root Nodules of Medicago truncatula and Is Regulated by Tyrosine Nitration

Melo

Silva²,

Ribeiro³

et al. 2011

Plant Physiology

119

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Nitric oxide (NO) is emerging as an important regulatory player in the Rhizobium-legume symbiosis, but its biological role in nodule functioning is still far from being understood. To unravel the signal transduction cascade and ultimately NO function, it is necessary to identify its molecular targets. This study provides evidence that glutamine synthetase (GS), a key enzyme for root nodule metabolism, is a molecular target of NO in root nodules of Medicago truncatula, being regulated by tyrosine (Tyr) nitration in relation to active nitrogen fixation. In vitro studies, using purified recombinant enzymes produced in Escherichia coli, demonstrated that the M. truncatula nodule GS isoenzyme (MtGS1a) is subjected to NO-mediated inactivation through Tyr nitration and identified Tyr-167 as the regulatory nitration site crucial for enzyme inactivation. Using a sandwich enzymelinked immunosorbent assay, it is shown that GS is nitrated in planta and that its nitration status changes in relation to active nitrogen fixation. In ineffective nodules and in nodules fed with nitrate, two conditions in which nitrogen fixation is impaired and GS activity is reduced, a significant increase in nodule GS nitration levels was observed. Furthermore, treatment of root nodules with the NO donor sodium nitroprusside resulted in increased in vivo GS nitration accompanied by a reduction in GS activity. Our results support a role of NO in the regulation of nitrogen metabolism in root nodules and places GS as an important player in the process. We propose that the NO-mediated GS posttranslational inactivation is related to metabolite channeling to boost the nodule antioxidant defenses in response to NO.

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“…NO is detectable inside the nodules even after the symbiosis is established. 22,23 It will be another interest whether NO in nodules contribute to induction of the systemic resistance of host plants.…”

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confidence: 99%