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Generation of Marked and Markerless Mutants in Model Cyanobacterial Species
Published on: May 29, 2016
DevT (Alr4674), resembling a Ser/Thr protein phosphatase, is essential for heterocyst function in the cyanobacterium
Javier Espinosa1, Thomas Brunner2, Nicole Fiedler2
1Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany.
Abstract:
Heterocyst-forming cyanobacteria are able to perform oxygenic photosynthesis and nitrogen fixation simultaneously in the same filament, by restricting the highly O(2)-sensitive nitrogenase to specialized cells, the heterocysts. A remarkable change in morphology and metabolism accompanies the differentiation of heterocysts, which only occurs when no source of combined nitrogen is available. In this study, we characterized DevT (Alr4674), a putative protein phosphatase from Anabaena PCC 7120. Mutants defective in devT are able to form morphologically mature heterocysts, which however cannot fix N(2), and the mutant cannot survive without a source of combined nitrogen. DevT shows homology to phosphatases of the PPP family and displays a Mn(2+)-dependent phosphatase activity that can be inhibited by phosphatase inhibitors and oxidizing conditions. DevT is constitutively expressed in both vegetative cells and heterocysts, and is not regulated by NtcA. The heterocyst regulator HetR may exert a certain inhibition on the expression of devT. Under diazotrophic growth conditions, DevT protein accumulates specifically in mature heterocysts. Therefore DevT plays a still unknown role in a late essential step of heterocyst differentiation.
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