N-methyladenine modification of DNA enhances RecA-mediated homologous recombination.

Both DNA methylation and homologous recombination (HR) are extensively studied. In bacteria, Dam methylation is the most studied DNA modification, while RecA-mediated HR is a primary mechanism to repair DNA damages including double-stranded breaks, single-stranded gaps, and stalled replication forks. While HR regulation by proteins is extensively studied, whether methylation of DNA itself directly affects the functions of RecA and HR remains unclear.

, a Gene Regulated by NtcA, Is Involved in the Optimization of Heterocyst Frequency in the Cyanobacterium sp. Strain PCC 7120.

In the filamentous multicellular cyanobacterium sp. strain PCC 7120, 5 to 10% of the cells differentiate into heterocysts, which are specialized in N fixation. Heterocysts and vegetative cells are mutually dependent for filament growth through nutrient exchange.

ppGpp metabolism is involved in heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120.

When deprived of a combined-nitrogen source in the growth medium, the filamentous cyanobacterium Anabaena sp. PCC 7120 (Anabaena) can form heterocysts capable of nitrogen fixation. The process of heterocyst differentiation takes about 20 to 24 h, during which extensive metabolic and morphological changes take place.