title: Core mutations of Synechococcus sp. PCC 7002 phycobilisomes: a spectroscopic study.
abstract: Three cyanobacterial strains harboring mutations affecting phycobilisome (PBS) cores were studied using steady state absorption and fluorescence and time-resolved fluorescence. The apcF mutant, missing beta 18, and the apcDF mutant, missing both alpha APB and beta 18, showed only small spectroscopic differences from the wild-type strain; their PBS emission was blue shifted by 10 nm, whereas their absorption spectra and time-resolved fluorescence kinetics were virtually unchanged. The third mutant studied was the apcE/C186S mutant in which the chromophore-binding cysteine-186 in the LCM99 polypeptide has been substituted with serine. The apcE/C186S mutant contained a modified chromophore which significantly changed the spectroscopic properties of the PBS complex. The apcE/C186S PBS absorbed more than the wild-type strain at 705 nm, and the emission spectrum gave two peaks at 660 nm and 715 nm. The time-resolved kinetics of the apcE/C186S mutant PBS were also significantly altered from those of the wild-type strain.
authors.affiliation: Chemical Biodynamics Division, Lawrence Berkeley Laboratory, University of California, Berkeley 94720.
authors.forename: Y M
authors.initials: YM
authors.lastname: Gindt
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: D A
authors.initials: DA
authors.lastname: Bryant
authors.forename: K
authors.initials: K
authors.lastname: Sauer
mesh_terms: D000458:Cyanobacteria / Q000235:genetics* / Q000378:metabolism; D045342:Light-Harvesting Protein Complexes; D045524:Phycobilisomes; D010860:Pigments, Biological / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry
chemical_list: D045342:Light-Harvesting Protein Complexes; D045524:Phycobilisomes; D010860:Pigments, Biological; D010940:Plant Proteins