The Presence of Chlorophyll b inSynechocystis sp. PCC 6803 Disturbs Tetrapyrrole Biosynthesis and Enhances Chlorophyll Degradation

In Vitro Reconstitution of Light-harvesting POR-Protochlorophyllide Complex with Protochlorophyllides a and b

“…The most likely candidates are proteins that could display (P)Chlide a oxygenase activity. Previous work has shown that there is a family of related proteins, which may exhibit such an activity (35)(36)(37)(38)(39)(40)(41). Tanaka et al (36) cloned a Chlamydomonas reinhardtii cDNA for a putative Chlide a oxygenase.…”

“…The Arabidopsis protein was expressed in bacteria and suggested to display Chlide a, but not Pchlide a, oxygenase activity (39). Recent work by Xu et al (40,41), however, highlighted that heterologous expression of the Arabidopsis Chlide a oxygenase in cyanobacteria leads to Pchl(ide) b and Chl(ide) b accumulation. Although this demonstrates that Chlide a oxygenase is well able to bind and convert Pchlide a to Pchlide b, it is not yet known whether Chlide a oxygenase is expressed in etiolated plants.…”

In Situ Conversion of Protochlorophyllideb to Protochlorophyllide a in Barley

“…42 and 43). According to recent work (44), Chlide a oxygenase is well able to accept both Pchlide a and Chlide a as substrate, although with different apparent affinities, but its expression in etiolated, illuminated, and lightadapted plants and its localization have not yet been examined.…”

Identification of plastid envelope proteins required for import of protochlorophyllide oxidoreductase A into the chloroplast of barley

“…Whereas Lls1 was proposed to operate as a suppressor of cell death in plants (37), Tic55 has been identified as part of the Tic complex (38). Cao, by contrast, is implicated in chlorophyllide b synthesis (40,41). All three proteins, Lls1, Tic55, and Cao, have in common a consensus sequence (Cys-X-His-X 16-17 -Cys-X 2 -His) for coordinating a Rieske-type [2Fe-2S] cluster (42) and a conserved mononuclear non-heme Fe-binding site (Glu-X 3-4 -Asp-X 2 -His-X 4-5 -His; ref.…”