Cloning,Expression, and Functions of the Phycoerythrin Lyases CpeY and CpeZ in Synechococcus sp. WH8102

Based on homology analysis of amino acid sequences, SYNW2013 and SYNW2012 from Synechococcus sp. WH8102 were found,which were similar to CpeY and CpeZ from Fremyella diplosiphon. The respective genes are named as cpeY-Syn and cpeZ-Syn, and were then constructed into different expression vectors via molecular cloning techniques.Using a heterologous coexpression system in Escherichia coli, CpeY-Syn and CpeZ-Syn could cooperatively catalyze the covalent attachment of phycoerythrobilin to CpeA.The experiments also showed that CpeY-Syn alone could ligate phycoerythrobilin to CpeA, but the yield of PEB-CpeA was lower than that in the presence of both CpeY-Syn and CpeZ-Syn. No fluorescent products were observed in the absence of CpeY-Syn. Similar to the CpcE/F lyases,which are responsible for the covalent attachment of phycocyanobilin to CpcA,the CpeY/Z-Syn lyases exclusively catalyzed the covalent attachment of phycoerythrobilin to CpeA.They belong to the E/F type of lyases of phycobiliproteins.