Oxygen sequestration by Leghemoglobin is positively regulated via its interaction with another late nodulin, Nlj16 of Lotus japonicus

Ghosh, Amit; Bhar, Kaushik; Siddhanta, Anirban

doi:10.1007/s13562-019-00494-3

Cited by 3 publications

(5 citation statements)

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“…Furthermore, we have also shown a novel interaction between LegH and Nlj16 in vitro and in vivo (Ghosh et al 2019). This interaction unveils yet another unexplored regulatory aspect of the oxygen sequestration ability of LegH.…”

Section: Discussionsupporting

confidence: 53%

“…An existence of conserved serine phosphorylation across the evolutionary border suggests that this phosphorylation of LegH might have a crucial regulatory role during SNF (Lin et al 2018). Furthermore, we have also shown a novel interaction between LegH and Nlj16 in vitro and in vivo (Ghosh et al 2019). This interaction unveils yet another unexplored regulatory aspect of the oxygen sequestration ability of LegH.…”

Section: Discussionmentioning

confidence: 78%

“…Results from our laboratory showed that the expression and co-localization of both LegH and Nlj16 proteins in root nodules of Lotus japonicus (Ghosh et al 2019). Notably, both the proteins co-localize in the cell periphery and in the cytosolic region in the nodule cells.…”

Section: Resultsmentioning

confidence: 99%

“…It was demonstrated that Nlj16 and Nlj16 like proteins localize to heterologous plant and yeast cell membranes (Kapranov et al 2001 and Ghosh et al 2015). Since, Nlj16 and LegH were shown to interact with each other in vivo (Ghosh et al 2019) therefore we speculated that Nlj16 has a role in the cell surface localization of LegH in the nodule cells. To address this hypothesis, we created transgenic plants of Lotus japonicus where Nlj16 was knocked down (KD) using siRNA containing gateway compatible binary vector system.…”

Section: Resultsmentioning

confidence: 99%

“…To address this issue, we have shown that while phosphorylation at specific serine residues of LegH negatively regulates its oxygen sequestration ability, the same is enhanced by the interaction of LegH with another late nodulin, Nodulin 16 of Lotus japonicus (Nlj16) in vitro (Bhar et al 2015 and Ghosh et al 2019). This protein-protein interaction was also shown to occur in 21 days old mature nodule of L. japonicus (Ghosh et al 2019). Here, in this report we have further characterized this interaction in vivo .…”

Section: Introductionmentioning

confidence: 99%

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Nodulin 16 of Lotus japonicus (Nlj16) regulates the recruitment of Leghemoglobin (LegH) to the infected nodule cell membrane during symbiotic nitrogen fixation

Ghosh¹,

Das

Ashrafi

et al. 2022

Preprint

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Nitrogenase that catalyses anaerobic symbiotic nitrogen fixation (SNF) in legumes is synthesized by rhizobium. Legume root cells express nodulin proteins after infection with rhizobia. Nodulins have been classified as early and late, reflecting the time points of their expression. Leghemoglobin (LegH), which is a classic example of a late nodulin, sequesters oxygen inside the nodule to protect the nitrogenase from oxygen toxicity to sustain SNF. Previous data from our laboratory demonstrated that phosphorylated LegH at S45 showed compromised oxygen sequestration in vitro due to structural disruption of the porphyrin binding pocket responsible for its oxygen binding. Moreover, we have demonstrated by using co-immunoprecipitation that LegH interacts both in vitro with Nodulin 16 of Lotus japonicus (Nlj16), another late nodulin. Fluorescence Immunohistochemistry (IHC) data shows that both LegH and Nlj16 are localized in the membrane and cytosol of infected cells. Notably, serine phosphorylation of LegH and interaction of Nlj16 with LegH respectively reduces and increases its in vitro oxygen sequestration ability. In this report, to further elucidate the spatio-temporal regulation of this interaction, we generated hairy root transgenic Lotus japonicus plants where Nlj16 has been knocked down by using siRNA. Most interestingly, our data shows that the membrane localization of LegH is obliterated in the Nlj16 knocked-down root cells infected with the cognate Rhizobia suggesting a distinct role of Nlj16 in its recruitment to the membrane of nodule cells.

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Section: Discussionsupporting

confidence: 53%

Section: Discussionmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%