Molecular cloning and expression analysis of a new bilin lyase: thecpcTgene encoding a bilin lyase responsible for attachment of phycocyanobilin to Cys-153 on the β-subunit of phycocyanin inArthrospira platensisFACHB314

Ran Zhang, Xiao-Ting Feng, Fei Wu, Yan Ding, Xiao-Nan Zang, Xue-Cheng Zhang, Ding-Yang Yuan, Bing-Ran Zhao

Index: Gene 544(2) , 191-7, (2014)

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Abstract

To study the assembly of phycocyanin β subunit, the gene cpcT was first cloned from Arthrospira platensis FACHB314. To explore the function of cpcT, the DNA of phycocyanin β subunit and cpcT were transformed into Escherichia coli BL21 with the plasmid pET-hox1-pcyA, which contained the genes hemeoxygenase 1 (Hox1) and ferredoxin oxidoreductase (PcyA) needed to produce phycocyanobilin. The transformed strains showed specific phycocyanin fluorescence, and the fluorescence intensity was stronger than the strains with only phycocyanin β subunit, indicating that CpcT can promote the assembly of phycocyanin to generate fluorescence. To study the possible binding sites of apo-phycocyanin and phycocyanobilin, the Cys-82 and Cys-153 of the β subunit were individually mutated, giving two kinds of mutants. The results show that Cys-153 maybe the active site for β subunit binding to phycocyanobilins, which is catalyzed by CpcT in A. platensis FACHB314.