Regulation of LHCa‐Polypeptide‐Biosynthesis in the Phototrophic Green Alga Chlamydobotrys stellata*

Abstract

The light-harvesting chlorophyll-protein system ofthe phototrophic alga Chlamydobotrys stellata consists of the common photosystem 11-related chlorophyll a/b-protein complex LHCII and a special photosystem I-connected chlorophyll protein complex, called LHCa (Brandt et al. 1982(Brandt et al. , 1983 which is present after cultivation of the algae with acetate as carbon source and in absence of carbon dioxide. LHCII consists of three polypeptides (M,.103 27.25.5 and 251, whereas only one polypeptide (Mr. lo3 24) was obtained after polyacrylamide gel electrophoresis of LHCa. The specific LHCII- precursor-polypeptides (M,.103 38, 32, 26) were among the translation products of poly(A+)mRNA from autotrophic or photoheterotrophic algae. The LHCa-precursor-polypeptide (M, 30 000) was found when the alga had been cultivated in the presence of acetate. The data support the assumption that LHCa-biosynthesis is controlled by the actual growth conditions at or close to the transcriptional level. Kev wnrdn

Influence of photoheterotrophy on the expression of chlorophyll a/b-binding proteins in the green alga Pyrobotrys stellata

“…As shown previously (Wiessner et al 1990), in the phototrophic P. stellata biosynthesis of CAB-proteins 53 is controlled at the transcriptional level. Therefore we employed northern blot analyses to investigate the expression of lhca5 and lhcb 1.…”

“…An oligo-dT primed cDNA expression library (A gtl 1) prepared from 2 h heterotrophically grown P. stellata was screened with polyclonal antibodies raised against SDS-PAGE purified CAB-proteins (Wiessner et al 1990). Inserts from positive phages were subcloned into Bluescript II KS(+) (Stratagene).…”

“…Total RNA was isolated as previously described (Wiessner et al 1990). Ten micrograms of total-RNA were used for electrophoresis in formaldehyde agarose-gels (Lehrach et al 1977).…”

“…A Agt 11 cDNA library was prepared with polyA + RNA extracted from P. stellata, and screened with antisera to CAB-proteins purified from this organism (Wiessner et al 1990). Two clones, CHL10 and CHL13, were isolated and sequenced.…”