A singular nitric oxide synthase with a globin domain found in Synechococcus PCC 7335 mobilizes N from arginine to nitrate

CORREA-ARAGUNDE, NATALIA; FORESI, NOELIA; DEL CASTELLO, FIORELLA; LAMATTINA, LORENZO

Scientific Reports

Springer New York

Año: 2018 vol. 8

The enzyme nitric oxide synthase (NOS) oxidizes L-arginine to NO and citrulline. In this work, wecharacterise the NOS from the cyanobacteria Synechococcus PCC 7335 (SyNOS). SyNOS possesses acanonical mammalian NOS architecture consisting of oxygenase and reductase domains. In addition,SyNOS possesses an unusual globin domain at the N-terminus. Recombinant SyNOS expressed inbacteria is active, and its activity is suppressed by the NOS inhibitor L-NAME. SyNOS allows E. coli togrow in minimum media containing L-arginine as the sole N source, and has a higher growth rate duringN defciency. SyNOS is expressed in Synechococcus PCC 7335 where NO generation is dependent onL-arginine concentration. The growth of Synechococcus is dramatically inhibited by L-NAME, suggestingthat SyNOS is essential for this cyanobacterium. Addition of arginine in Synechococcus increases thephycoerythrin content, an N reservoir. The role of the novel globin domain in SyNOS is discussed as anevolutionary advantage, conferring new functional capabilities for N metabolism.