Large scale cultivation of microalgae holds the demanding promise to support a biomass-based economy dealing with the production of renewable biological resources and their conversion into food, feed, bioenergy and bio-based products1. Intense research efforts are hence focused on selection of highly productive strains, and/or engineering of well-known genotypes to introduce competitive traits enabling their adaptation to the industrial cultivation conditions. Indeed, photosynthesis is one of the main target of this research field, being tightly linked to the sustainable production of biomass and added-value compounds2,3. The photosynthetic machinery is a smart assembly of ad hoc light collectors, protein-metal clusters, and redox biocatalysts enabling the conversion of solar energy into chemical energy. The process relays on the transduction of photo-excitation events into transmembrane charge-separated states that occurs with very high quantum efficiency, and a series of electron transfer reactions leading to the production of all the goods that fuels our daily life. In addition, photosynthesis gains renewed interest due to the possibility to integrate whole plant cells or their photosynthetic sub-components into optoelectronic devices such as biosensors for environmental monitoring, and/or bio-photoelectro-chemical cells for clean energy production2. In the quest to identify parameters correlated with a more efficient photosynthetic performance or biotechnologically useful phenotypes, we studied the structure/function relationships occurring in Chlamydomonas reinhardtii strains hosting single aminoacidic substitutions in the photosystem II D1 (PSII-D1) protein. The mutants were produced by combining in silico studies with an in vitro directed evolution approach followed by site-directed mutagenesis experiments4,5. Selected mutants were characterized determining the growth rate, pigment content, electron transport efficiency of PSII and rate of oxygen evolution. The performed studies enabled the identification of phenotypes having enhanced stability and photosynthetic performance under stressful conditions6, and improved sensitivity to triazines and urea type herbicides7. Furthermore, a model of the three-dimensional structure of Chlamydomonas PSII was achieved by molecular dynamics simulations providing insights into the mechanisms of plastoquinol-plastoquinone exchange8,9. 1. European Commission 2012, SWD(2012) 11 final; 2. Frontiers in Chemistry, 2014,2:36; 3. ChemSusChem, 2015, 8:2854-2866; 4. Protein Science, 2009, 18:2139-2151; 5. PLoS ONE 2011, 6:e16216; 6. PloS One, 2013, 8:e64352; 7. PloS ONE 2013, 8:e61851; 8. Current Protein and Peptide Science, 2014, 15:285-295; 9. Photosynthesis research, 2016, Doi:10.1007/s11120-016-0292-4.
Photochemical characterization of Chlamydomonas mutants for biotechnological applications
MD Lambreva;A Antonacci;V Scognamiglio;G Rea
2016
Abstract
Large scale cultivation of microalgae holds the demanding promise to support a biomass-based economy dealing with the production of renewable biological resources and their conversion into food, feed, bioenergy and bio-based products1. Intense research efforts are hence focused on selection of highly productive strains, and/or engineering of well-known genotypes to introduce competitive traits enabling their adaptation to the industrial cultivation conditions. Indeed, photosynthesis is one of the main target of this research field, being tightly linked to the sustainable production of biomass and added-value compounds2,3. The photosynthetic machinery is a smart assembly of ad hoc light collectors, protein-metal clusters, and redox biocatalysts enabling the conversion of solar energy into chemical energy. The process relays on the transduction of photo-excitation events into transmembrane charge-separated states that occurs with very high quantum efficiency, and a series of electron transfer reactions leading to the production of all the goods that fuels our daily life. In addition, photosynthesis gains renewed interest due to the possibility to integrate whole plant cells or their photosynthetic sub-components into optoelectronic devices such as biosensors for environmental monitoring, and/or bio-photoelectro-chemical cells for clean energy production2. In the quest to identify parameters correlated with a more efficient photosynthetic performance or biotechnologically useful phenotypes, we studied the structure/function relationships occurring in Chlamydomonas reinhardtii strains hosting single aminoacidic substitutions in the photosystem II D1 (PSII-D1) protein. The mutants were produced by combining in silico studies with an in vitro directed evolution approach followed by site-directed mutagenesis experiments4,5. Selected mutants were characterized determining the growth rate, pigment content, electron transport efficiency of PSII and rate of oxygen evolution. The performed studies enabled the identification of phenotypes having enhanced stability and photosynthetic performance under stressful conditions6, and improved sensitivity to triazines and urea type herbicides7. Furthermore, a model of the three-dimensional structure of Chlamydomonas PSII was achieved by molecular dynamics simulations providing insights into the mechanisms of plastoquinol-plastoquinone exchange8,9. 1. European Commission 2012, SWD(2012) 11 final; 2. Frontiers in Chemistry, 2014,2:36; 3. ChemSusChem, 2015, 8:2854-2866; 4. Protein Science, 2009, 18:2139-2151; 5. PLoS ONE 2011, 6:e16216; 6. PloS One, 2013, 8:e64352; 7. PloS ONE 2013, 8:e61851; 8. Current Protein and Peptide Science, 2014, 15:285-295; 9. Photosynthesis research, 2016, Doi:10.1007/s11120-016-0292-4.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
