MpeY family

The mpeY gene is present in the "PEII subregion" of the "phycobilisome rod gene region" of all PEII-containing marine Synechococcus strains belonging to pigment types 3a and 3dA (Sanfilippo et al. 2019; Grébert et al. 2021); it is found at the same position as mpeQ in the phycobilisome gene region of pigment types 3c and 3dB (Grébert et al. 2021, 2022). MpeW was biochemically characterized as a PEB:Cys-83 alpha-PEII lyase in the pigment 3dA Synechococcus strain RS9916 (Sanfilippo et al. 2019). In Synechococcus pigment type 3a strains, this position therefore constitutively binds a PEB, whereas in pigment type 3dA strains, this position binds a PUB in blue light and a PEB in green light, as the result of a competition between MpeY and the PEB lyase-isomerase MpeZ, which is specifically and strongly activated in blue light but repressed in green light (Shukla et al. 2012; Humily et al. 2013).