PCR amplified ORF 469 fragment from Synechocystis sp . PCC 6803 was cloned into pUC118 and a construct was made in which part of ORF 469 was deleted and replaced by erythromycin resistance cassette. Tran...PCR amplified ORF 469 fragment from Synechocystis sp . PCC 6803 was cloned into pUC118 and a construct was made in which part of ORF 469 was deleted and replaced by erythromycin resistance cassette. Transformation of wild type strain of Synechocystis sp . PCC 6803 with this construct yielded a mutant in which ORF 469 was deleted. In the resulting mutant, the light independent pathway of chlorophyll biosynthesis was inactivated and availability of chlorophyll was fully dependent on light. When propagated the mutant in dark, the chlorophyll was non detectable and protochlorophyllide with 645?nm fluorescence emission peak was accumulated. Meanwhile, the fluorescence emission peaks (excited at 435?nm) of thylakoids at 685?nm, 695?nm and 725?nm, which represented relative chlorophyll\|binding proteins, disappeared. Upon return of dark\|grown ORF 469 mutant to the light, greening occurred and chlorophyll was synthesized to assembly fluorescence emission components in photosystems. Newly synthesized chlorophyll combined the fluorescence component of 685?nm at first, then 725?nm and 695?nm at last, which indicates a pecking order for biogenesis of chlorophyll binding proteins when availability of chlorophyll is limited. The mutant lacking ORF 469 in Synechocystis sp . PCC 6803 was suggested as an excellent cyanobacterial system for studies on the interactions between chlorophyll and chlorophyll binding proteins in photosystems.展开更多
基金the National Nature Science Foundation of China !(No. 39870 0 6 4and 495 2 5 2 0 5 )partly by Na tional Nature Science
文摘PCR amplified ORF 469 fragment from Synechocystis sp . PCC 6803 was cloned into pUC118 and a construct was made in which part of ORF 469 was deleted and replaced by erythromycin resistance cassette. Transformation of wild type strain of Synechocystis sp . PCC 6803 with this construct yielded a mutant in which ORF 469 was deleted. In the resulting mutant, the light independent pathway of chlorophyll biosynthesis was inactivated and availability of chlorophyll was fully dependent on light. When propagated the mutant in dark, the chlorophyll was non detectable and protochlorophyllide with 645?nm fluorescence emission peak was accumulated. Meanwhile, the fluorescence emission peaks (excited at 435?nm) of thylakoids at 685?nm, 695?nm and 725?nm, which represented relative chlorophyll\|binding proteins, disappeared. Upon return of dark\|grown ORF 469 mutant to the light, greening occurred and chlorophyll was synthesized to assembly fluorescence emission components in photosystems. Newly synthesized chlorophyll combined the fluorescence component of 685?nm at first, then 725?nm and 695?nm at last, which indicates a pecking order for biogenesis of chlorophyll binding proteins when availability of chlorophyll is limited. The mutant lacking ORF 469 in Synechocystis sp . PCC 6803 was suggested as an excellent cyanobacterial system for studies on the interactions between chlorophyll and chlorophyll binding proteins in photosystems.
