Date of Award

12-2006

Degree Type

Thesis

Degree Name

M.S.

Degree Program

Biological Sciences

Department

Biological Sciences

Major Professor

Schluchter, Wendy

Second Advisor

Timpte, Candace

Third Advisor

Clancy, Mary

Abstract

The goal of this research is to identify and characterize the enzymes (lyases) responsible for chromophore (bilin) attachment to phycobiliproteins (light harvesting) in cyanobacteria. Candidates for these lyases were first identified in Fremyella diplosiphon as cpeS and cpeT. In Synechococcus sp. PCC 7002, there are three cpeS-like genes (named cpcS, cpcU, and cpcV) and one cpeT-like gene (named cpcT). These genes were cloned, overexpressed, and purified from E. coli. The CpcS and CpcU proteins form a 1:1 complex and catalyze the addition of phycocyanobilin (PCB) to â-82 cysteinyl residue on phycocyanin (PC) in vitro. Tryptic digestion and C18 RP-HPLC confirmed that CpcSU attached bilin at â-82 cysteine. CpcT was also shown to be a lyase specific for â-153 cysteine as confirmed by tryptic digestion and C18 RP-HPLC. CpcSU together and CpcT alone act as phycobiliprotein lyases that added PCB to â- 82 and â-153 cysteinyl residues of phycocyanin respectively, making these proteins a new family of phycobiliprotein lyases.

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The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

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