title: Regulation of chlorophyll apoprotein expression and accumulation. Requirements for carotenoids and chlorophyll.
abstract: Chlorophyll apoprotein accumulation and expression were examined in mutants of Chlamydomonas reinhardtii blocked at specific steps of carotenoid or chlorophyll synthesis. In the absence of carotenoids: 1) apoproteins of the core and light-harvesting complexes of photosystem I (CCI and LHCI, respectively) and photosystem II (CCII and LHCII, respectively) do not accumulate; 2) mRNAs for the CCI, CCII, and LHCII apoproteins accumulate to normal levels; and 3) synthesis of the chlorophyll apoproteins is differentially affected, or in some cases, not affected. In the absence of chlorophylls: 1) the apoproteins fail to accumulate; 2) mRNA levels for CCI and CCII apoproteins are relatively unchanged; 3) levels of LHCII apoprotein mRNA, but not rates of LHCII mRNA synthesis, are reduced in a light-dependent chlorophyll-synthesis mutant (ya12); and 4) synthesis of chlorophyll apoproteins is differentially affected or not affected in the case of several chloroplast-encoded apoproteins. These results demonstrate a direct role for carotenoids as well as chlorophylls in the stabilization of certain chlorophyll apoproteins and, for others, possibly in their translation. The data also indicate a role for chlorophyll synthesis in the stability of LHCII mRNA.
authors.affiliation: Department of Botany, University of Georgia, Athens 30602.
authors.forename: D L
authors.initials: DL
authors.lastname: Herrin
authors.forename: J F
authors.initials: JF
authors.lastname: Battey
authors.forename: K
authors.initials: K
authors.lastname: Greer
authors.forename: G W
authors.initials: GW
authors.lastname: Schmidt
mesh_terms: D000818:Animals; D001059:Apoproteins / Q000235:genetics* / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D002338:Carotenoids / Q000378:metabolism*; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism; D002734:Chlorophyll / Q000235:genetics* / Q000378:metabolism; D002736:Chloroplasts; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation; D011499:Protein Processing, Post-Translational; D012313:RNA / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional
chemical_list: D001059:Apoproteins; D008565:Membrane Proteins; D002734:Chlorophyll; D002338:Carotenoids; D012313:RNA