Date of Award

Spring 5-2013

Degree Type


Degree Name


Degree Program

Biological Sciences


Biological Sciences

Major Professor

Schluchter, Wendy

Second Advisor

Liu, Zhengchang

Third Advisor

Clancy, Mary


Phycoerythrin (PE) present on the outer phycobilisome (PBS) rods in Fremyella diplosiphon contains covalently attached phycoerythrobilin (PEB) chromophores for efficient photosynthetic light capture. Chromophore ligation on phycobiliprotein subunits occurs through bilin lyase catalyzed reactions. The cpeY and cpeZ genes in F. diplosiphon were shown to attach PEB on alph-82 of PE. To better understand the individual functions of cpeY and cpeZ in native cyanobacteria, we characterized PBS and PE purified from cpeY and cpeZ deletion mutants and compared them with wild type (WT). Both cpeY and cpeZ mutants generated much less PE than WT as well as assembling much less PE into the PBS. PE purified from cpeY mutant had phycocyanobilin on alpha-PE in place of PEB. The mutation of cpeZ affected the biosynthesis and accumulation of beta-PE with a red-shifted absorbance compared to WT PE. CpeY was shown to function as a bilin lyase, and CpeZ possibly functions as a chaperone.


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