Transcriptional regulation of development in heterocyst-forming cyanobacteria

Publication date: Available online 30 April 2018Source: Biochimica et Biophysica Acta (BBA) - Gene Regulatory MechanismsAuthor(s): Enrique Flores, Silvia Picossi, Ana Valladares, Antonia HerreroAbstractFilamentous, heterocyst-forming cyanobacteria are among the simplest multicellular systems in Nature. In the absence of combined nitrogen, the filaments consist of vegetative cells that fix CO2 through oxygenic photosynthesis and micro-oxic heterocysts specialized for the fixation of N2 in a proportion of about 10 to 1. The development of a heterocyst-containing filament involves differentiation of vegetative cells into heterocysts in a process that requires a distinct gene expression program. Two transcription factors are strictly required, NtcA and HetR. The CRP-family protein NtcA directly activates the expression of multiple genes during heterocyst differentiation – in some cases assisted by coactivators including HetR – and in mature heterocysts, whereas HetR is needed to build high NtcA levels in differentiating heterocysts and directly activates some particular genes. A few other regulators of gene expression participate at specific differentiation steps, and a specific transcription factor, CnfR, activates nif gene expression under the micro-oxic conditions of the heterocyst.
Source: Biochimica et Biophysica Acta (BBA) Gene Regulatory Mechanisms - Category: Genetics & Stem Cells Source Type: research
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