Programmed DNA Rearrangements in Cyanobacteria
Three developmentally programmed DNA rearrangements occur during hetero-cyst differentiation in the nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120 (Anabaena PCC 7120). All three rearrangements involve the excision of an element from the chromosome by site-specific recombination and each requires an element-encoded recombinase. Each element is harbored in a hetero-cyst-specific gene that is required for the production of a fully functional heterocyst. Precise excision of the elements is necessary to restore these genes. Elements similar to these Anabaena PCC 7120 elements have been found in a variety of heterocystous cyanobacterial strains.
KeywordsHeterocyst Differentiation Heterocyst Development nifD Gene NtcA Binding Site Upstream Start Codon
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