DevT (Alr4674), resembling a Ser/Thr protein phosphatase, is essential for heterocyst function in the cyanobacterium Anabaena sp. PCC 7120.
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.
Espinosa
Javier
J
Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany.
Brunner
Thomas
T
Lehrstuhl für Zellbiologie und Pflanzenphysiologie, University of Regensburg, D-93040 Regensburg, Germany.
Fiedler
Nicole
N
Lehrstuhl für Zellbiologie und Pflanzenphysiologie, University of Regensburg, D-93040 Regensburg, Germany.
Forchhammer
Karl
K
Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany.
Muro-Pastor
Alicia M
AM
Instituto de Bioquímica Vegetal y Fotosíntesis (CSIC and Universidad de Sevilla), Centro de Investigaciones Científicas Isla de la Cartuja, E-41092 Sevilla, Spain.
Maldener
Iris
I
Lehrstuhl für Zellbiologie und Pflanzenphysiologie, University of Regensburg, D-93040 Regensburg, Germany.|Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions, University of Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany.
D017033:Anabaena / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000235:genetics / Q000378:metabolism*; D013912:Threonine / Q000378:metabolism*
D001426:Bacterial Proteins; D013912:Threonine; D012694:Serine; D010749:Phosphoprotein Phosphatases