Disruption of the plastid ycf10 open reading frame affects uptake of inorganic carbon in the chloroplast of Chlamydomonas

Article Article scientifique Article Disruption of the plastid ycf10 open reading frame affects uptake of inorganic carbon in the chloroplast of Chlamydomonas eng 1997 author Rolland Norbert Christian 88246 author Dorne Albert-Jean author Amoroso Gabi author Sültemeyer Dieter F. author Joyard Jacques author Rochaix Jean-David 25289 6713-6726 10.1093/emboj/16.22.6713 0261-4189 http://emboj.embopress.org/cgi/doi/10.1093/emboj/16.22.6713 The product of the chloroplast ycf10 gene has been localized in the inner chloroplast envelope membrane (Sasaki et al., 1993) and found to display sequence homology with the cyanobacterial CotA product which is altered in mutants defective in CO₂ transport and proton extrusion (Katoh et al., 1996a,b). In Chlamydomonas reinhardtii, ycf10, located between the psbI and atpH genes, encodes a putative hydrophobic protein of 500 residues, which is considerably larger than its higher plant homologue because of a long insertion that separates the conserved N and C termini. Using biolistic transformation, we have disrupted ycf10 with the chloroplast aadA expression cassette and examined the phenotype of the homoplasmic transformants. These were found to grow both photoheterotrophically and photoautotrophically under low light, thereby revealing that the Ycf10 product is not essential for the photosynthetic reactions. However, under high light these transformants did not grow photoautotrophically and barely photoheterotrophically. The increased light sensitivity of the transformants appears to result from a limitation in photochemical energy utilization and/or dissipation which correlates with a greatly diminished photosynthetic response to exogenous (CO₂ + HCO₃₋), especially under conditions where the chloroplast inorganic carbon transport system is not induced. Mass spectrometric measurements with either whole cells or isolated chloroplasts from the transformants revealed that the CO₂ and HCO₃₋ uptake systems have a reduced affinity for their substrates. The results suggest the existence of a ycf10‐dependent system within the plastid envelope which promotes efficient inorganic carbon (Ci) uptake into chloroplasts. Chlamydomonas reinhardtii CO2 uptake Light sensitivity Mass-spectrometry Ycf10 Dewey 570 Dewey 580 Swiss National Science Foundation 31.34014.92 CH 43 Département de biologie moléculaire 161 45 Département des sciences végétales 163 false EMBO Journal 16 22 10c0a994-5660-4689-b338-964eaf9222c1 Article (Published version) Restricted 006713.pdf 1448644 application/pdf restrictedAccess Faculté des sciences / Section de biologie / Département de biologie moléculaire Faculté des sciences / Section de biologie / Département des sciences végétales

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Disruption of the plastid ycf10 open reading frame affects uptake of inorganic carbon in the chloroplast of Chlamydomonas	EMBO Journal			1997	319	0

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Rolland, Norbert Christian