NITROGENASE-SPECIFIC PROTEOLYTIC ACTIVITY IN THE UNICELLULAR CYANOBACTERIUM <i>GLOEOTHECE</i>

Dougherty, Lisa J; Brown, Eric G.; Gallon, John

doi:10.1042/bst024401s

Cited by 4 publications

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“…2d), indicating that virtually all the cells express nitrogenase and maintain enzyme activity constitutively in CL-acclimated culture. As the anti-Feprotein antibody used in this study reacted with proteins smaller than 35 kDa that were probably the degradation products of the Fe-protein (Dougherty et al, 1996), as well as with the Fe-protein (Figs 1c, 2c), the proportion of the Fe-protein-containing cells would be overestimated. However, the calculations mentioned above are basically not changed because the overestimation of the Fe-proteincontaining cells may occur to a similar extent in CLacclimated culture and in LD-acclimated culture; the amount of the Fe-protein (41 and 37 kDa, indicated by an arrow in Fig.…”

Section: Discussionmentioning

confidence: 93%

Diazotrophy under continuous light in a marine unicellular diazotrophic cyanobacterium, Gloeothece sp. 68DGA

et al. 2008

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Nitrogenase is extremely sensitive to molecular oxygen (O 2 ), and unicellular diazotrophic cyanobacteria separate nitrogen (N 2 )-fixation and photosynthesis to protect nitrogenase from O 2 produced by photosynthesis. When grown under 12 h light/12 h dark cycles (LD), the marine unicellular diazotrophic cyanobacterium Gloeothece sp. 68DGA expressed the nitrogenase protein and its activity (acetylene reduction activity) only during the dark phase. However, this strain was able to grow diazotrophically under continuous light (CL). To determine whether nitrogenase synthesis and N 2 -fixation are temporally separated from photosynthesis in the Gloeothece cells that have fully acclimated to CL, the proportion of cells containing nitrogenase (the Fe-protein of nitrogenase) in the culture was measured using an immunocytochemical technique. Cells were grown in a continuous-culture device to maintain constant cell density. Under LD, the cells showed diurnal oscillation of nitrogenase activity, photosynthesis, respiration and the expression and the abundance of the Fe-protein. The oscillation was gradually reduced after the transfer of the cells to CL, and was lost after 23-25 days of cultivation under CL. In CL-acclimated cultures, the Fe-protein was always detected in about 94 % of the cells, although the nitrogenase activity was about one-third of the maximum activity in LD-acclimated cultures. These results suggest that synthesis of nitrogenase proceeds without diurnal oscillation in the CL-acclimated cells of Gloeothece sp. 68DGA. As the respiration rate in CL-acclimated culture was as high as the maximum rate observed in LD-acclimated culture, O 2 -uptake mechanism(s) may have been upregulated to maintain low intracellular pO 2 .

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Section: Discussionmentioning

confidence: 93%

Diazotrophy under continuous light in a marine unicellular diazotrophic cyanobacterium, Gloeothece sp. 68DGA

et al. 2008

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“…strain RF‐1 has been proposed to be preferentially targeted for proteolytic degradation [19]. However, in extracts of Gloeothece , both forms of the Fe‐protein appeared to be equally sensitive to degradation, both in vivo [8,9] and in vitro [30]. The functional significance of the observed palmitoylation of the Fe‐protein of Gloeothece nitrogenase therefore remains unclear.…”

Section: Resultsmentioning

confidence: 99%

A novel covalent modification of nitrogenase in a cyanobacterium

et al. 2000

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In extracts of the unicellular cyanobacterium Gloeothece, the Fe-protein of nitrogenase can be separated by SDS-PAGE into two antigenically identifiable components. Unlike the situation in photosynthetic bacteria such as Rhodospirillum rubrum, these two forms do not arise from covalent modification of the protein by ADP-ribosylation. Rather, the Fe-protein of Gloeothece nitrogenase is subjected to modification by palmitoylation.

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N2 Fixation by Non-Heterocystous Cyanobacteria

Gallon¹

Genetics and Regulation of Nitrogen Fixation in Free-Living Bacteria

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NITROGENASE-SPECIFIC PROTEOLYTIC ACTIVITY IN THE UNICELLULAR CYANOBACTERIUM GLOEOTHECE

Cited by 4 publications

References 0 publications

Diazotrophy under continuous light in a marine unicellular diazotrophic cyanobacterium, Gloeothece sp. 68DGA

Diazotrophy under continuous light in a marine unicellular diazotrophic cyanobacterium, Gloeothece sp. 68DGA

A novel covalent modification of nitrogenase in a cyanobacterium

N2 Fixation by Non-Heterocystous Cyanobacteria

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