I am a plant and environmental biologist studying molecular mechanisms which allowed photosynthetic organsms to conquer land and optimize primary productivity in different environments with particular focus in light harvesting and light use efficiency. Applied aspects of our work include improving crop photosynthetic efficiency and resistance to abiotic stresses. Complementary research focuses on biofuel production to minimize CO2 release in athmosphere and air pollution.
Magnetic Nanoparticles extracted from magnetotactic bacteria as contrast agents for MRI Pasquina ... more Magnetic Nanoparticles extracted from magnetotactic bacteria as contrast agents for MRI Pasquina Marzola, Leonardo Ghin, Stefano Tambalo, Giamaica Conti, Silvia Mannucci, Alice Busato, Elvira Fantechi, Claudia Innocenti, Claudio Sangregorio, Alessandro Lascialfari, Tomas Orlando, Roberto Bassi, and Andrea Sbarbati Department of Computer Science, University of Verona, Verona, Italy, Department of Biotechnology, University of Verona, Verona, Italy, Department of Neurological and Movement Science, University of Verona, Verona, Italy, INSTM-LaMM, Dept. of Chemistry, University of Florence, Florence, Italy, Department of Physics, University of Milan, Milan, Italy
SummaryIn natural ecosystems, plants compete for space, nutrients and light. The optically dense ... more SummaryIn natural ecosystems, plants compete for space, nutrients and light. The optically dense canopies limit the penetration of photosynthetically active radiation and light often becomes a growth‐limiting factor for the understory. The reduced availability of photons in the lower leaf layers is also a major constraint for yield potential in canopies of crop monocultures. Traditionally, crop breeding has selected traits related to plant architecture and nutrient assimilation rather than light use efficiency. Leaf optical density is primarily determined by tissue morphology and by the foliar concentration of photosynthetic pigments (chlorophylls and carotenoids). Most pigment molecules are bound to light‐harvesting antenna proteins in the chloroplast thylakoid membranes, where they serve photon capture and excitation energy transfer toward reaction centers of photosystems. Engineering the abundance and composition of antenna proteins has been suggested as a strategy to improve lig...
Abstract Photosynthetic microalgae hold great potential as light-driven heterologous protein expr... more Abstract Photosynthetic microalgae hold great potential as light-driven heterologous protein expression hosts. In particular, the algal chloroplast is an ideal sub-cellular site for the compartmentalized synthesis and accumulation of high-value recombinant proteins. However, full integration of transplastomic algal biotechnology in the large-scale production of biocatalysts still suffers from major bottlenecks, such as genetic instability and pest contamination. To enhance the reliability of plastid-based algal expression platforms we developed a self-reinforcing genetic system in Chlamydomonas reinhardtii. We transformed the plastome with a bifunctional transgene encoding an in vivo cleavable fusion polypeptide composed of a hyperthermophilic cellulase and the phosphite dehydrogenase PTXD. The dual use of phosphite as a low-cost, environmentally friendly selective agent and fertilizer afforded axenic algal cultivation via mixotrophic metabolism and efficient expression of the hydrolytic enzyme. This study provides an example of chloroplast genetic engineering in which biosafety is integrated in the sustainable management of microalgal monocultures to produce enzymes with industrial applications.
ABSTRACT Definition of the SubjectAlgae are oxygenic photoautotrophs, offering a very high level ... more ABSTRACT Definition of the SubjectAlgae are oxygenic photoautotrophs, offering a very high level of biodiversity and thus suitable for different practical applications. Today, they are mainly cultivated for human/animal food or to extract high-value chemicals and pharmaceuticals. However, their exploitation could be extended. Algae are attractive as high yield biomass producers, because of the short life cycle, the ability to grow up to very high cell densities, and the easy large-scale cultivation that does not compete with other demands such as those of conventional crops agriculture. Algae can be a resource of renewable, sustainable biofuels. In addition, they can be transformed into “cell factories” to produce recombinant proteins of interest for pharmaceutical companies.IntroductionAlgae are described as “lower” plants that never have true stems, roots, and leaves, and grow photoautotrophically by performing oxygenic photos ...
We demonstrate an ultrabroadband two-dimensional electronic spectrometer that maps energy flow ac... more We demonstrate an ultrabroadband two-dimensional electronic spectrometer that maps energy flow across the visible range. This apparatus enables observation of previously unexplored carotenoid-mediated light-harvesting dynamics in plants, including identification of a debated carotenoid dark state.
This book introduces the basic physical, chemical, and biological principles underlying the first... more This book introduces the basic physical, chemical, and biological principles underlying the first steps in photosynthesis: light absorption, excitation energy transfer, and charge separation. In Part 1, we introduce pigments and their spectroscopic/ redox properties. In Part 2, pigment-proteins as they occur in various natural systems (plants, algae, photosynthetic bacteria) are described, including the regulation of light harvesting. Part 3 deals with the physics underlying light harvesting: energy transfer and electron transport. Part 4 introduces basic and advanced spectroscopic methods, including data analysis. In Part 5, we discuss artificial and natural photosynthetic systems, how they are assembled, and what the energy transfer properties are
Green plants prevent photodamage under high light conditions by dissipating excess energy as heat... more Green plants prevent photodamage under high light conditions by dissipating excess energy as heat. Conformational changes of the photosynthetic antenna complexes activate dissipation by leveraging the sensitivity of the photophysics of the chlorophyll and carotenoids to their surrounding protein. However, the mechanisms and site of dissipation are still debated, largely due to two challenges. First, experiments have been performed in detergent, which can induce non-native conformations, or in vivo, where contributions from the multiple complexes cannot be disentangled and are further obfuscated by laser-induced artifacts. Second, because of the ultrafast timescales and large energy gaps involved, measurements lacked the temporal or spectral requirements. Here, we overcome both challenges by applying ultrabroadband two-dimensional electronic spectroscopy to the principal antenna complex, light-harvesting complex II, in a near-native membrane. The spectra show that the membrane enhanc...
Green plants prevent photodamage under high light conditions by dissipating excess energy as heat... more Green plants prevent photodamage under high light conditions by dissipating excess energy as heat. Conformational changes of the photosynthetic antenna complexes activate dissipation by leveraging the sensitivity of the photophysics of the chlorophyll and carotenoids to their surrounding protein. However, the mechanisms and site of dissipation are still debated, largely due to two challenges. First, because of the ultrafast timescales and large energy gaps involved, measurements lacked the temporal or spectral requirements. Second, experiments have been performed in detergent, which can induce non-native conformations, or in vivo, where contributions from the multiple complexes cannot be disentangled and are further obfuscated by laser-induced artifacts. Here, we overcome both challenges by applying ultrabroadband two-dimensional electronic spectroscopy to the principal antenna complex, light-harvesting complex II, in a near-native membrane. The membrane enhances two dissipative pat...
Proceedings of the National Academy of Sciences, 2019
Significance Protein flexibility is essential for the robustness of biological systems, yet the d... more Significance Protein flexibility is essential for the robustness of biological systems, yet the dynamics underlying this flexibility are difficult to observe, because they are small, fast, and stochastic. Photoprotection in plants is critical for robust growth under highly variable sunlight, but the complexity of photosynthetic proteins means that identifying conformational states and dynamics responsible is challenging. Here, we develop a method using the correlation function of the fluorescence lifetime to characterize multiple dynamical processes in single proteins. By applying this method to the protein Light-Harvesting Complex Stress Related 1 (LHCSR1), we identify two local protein motions that control quenching of excess sunlight, which is a photoprotective effect. Our analytical approach enables a structure-based understanding of the photoprotective mechanisms in green plants.
We utilise ultrabroadband two-dimensional electronic spectroscopy to map out pathways of energy f... more We utilise ultrabroadband two-dimensional electronic spectroscopy to map out pathways of energy flow in LHCII across the entire visible region. In addition to the well-established, low-lying chlorophyll Qy bands, our results reveal additional pathways of energy relaxation on the higher-lying excited states involving the S2 energy levels of carotenoids, including ultrafast carotenoid-to-chlorophyll energy transfer on 90-150 fs timescales.
Marine diatoms are prominent phytoplankton organisms, optimally performing photosynthesis in extr... more Marine diatoms are prominent phytoplankton organisms, optimally performing photosynthesis in extremely variable environments. Diatoms possess a strong ability to dissipate excess absorbed energy as heat via non-photochemical quenching (NPQ). This process relies on changes in carotenoid pigment composition (xanthophyll cycle) and on specific members of the light-harvesting complex (LHC) family specialized in photoprotection (LHCX), which potentially act as NPQ effectors. However, the link between light stress, NPQ, and the existence of different LHCX isoforms is not understood in these organisms. Using picosecond fluorescence analysis, we observed two types of NPQ in the pennate diatom Phaeodactylum tricornutum, depending on light conditions. Short exposure of low-light acclimated cells to high light triggers the onset of energy quenching close to the core of Photosystem II, while prolonged light stress activates NPQ in the antenna. Biochemical analysis indicates a link between the c...
Magnetic Nanoparticles extracted from magnetotactic bacteria as contrast agents for MRI Pasquina ... more Magnetic Nanoparticles extracted from magnetotactic bacteria as contrast agents for MRI Pasquina Marzola, Leonardo Ghin, Stefano Tambalo, Giamaica Conti, Silvia Mannucci, Alice Busato, Elvira Fantechi, Claudia Innocenti, Claudio Sangregorio, Alessandro Lascialfari, Tomas Orlando, Roberto Bassi, and Andrea Sbarbati Department of Computer Science, University of Verona, Verona, Italy, Department of Biotechnology, University of Verona, Verona, Italy, Department of Neurological and Movement Science, University of Verona, Verona, Italy, INSTM-LaMM, Dept. of Chemistry, University of Florence, Florence, Italy, Department of Physics, University of Milan, Milan, Italy
SummaryIn natural ecosystems, plants compete for space, nutrients and light. The optically dense ... more SummaryIn natural ecosystems, plants compete for space, nutrients and light. The optically dense canopies limit the penetration of photosynthetically active radiation and light often becomes a growth‐limiting factor for the understory. The reduced availability of photons in the lower leaf layers is also a major constraint for yield potential in canopies of crop monocultures. Traditionally, crop breeding has selected traits related to plant architecture and nutrient assimilation rather than light use efficiency. Leaf optical density is primarily determined by tissue morphology and by the foliar concentration of photosynthetic pigments (chlorophylls and carotenoids). Most pigment molecules are bound to light‐harvesting antenna proteins in the chloroplast thylakoid membranes, where they serve photon capture and excitation energy transfer toward reaction centers of photosystems. Engineering the abundance and composition of antenna proteins has been suggested as a strategy to improve lig...
Abstract Photosynthetic microalgae hold great potential as light-driven heterologous protein expr... more Abstract Photosynthetic microalgae hold great potential as light-driven heterologous protein expression hosts. In particular, the algal chloroplast is an ideal sub-cellular site for the compartmentalized synthesis and accumulation of high-value recombinant proteins. However, full integration of transplastomic algal biotechnology in the large-scale production of biocatalysts still suffers from major bottlenecks, such as genetic instability and pest contamination. To enhance the reliability of plastid-based algal expression platforms we developed a self-reinforcing genetic system in Chlamydomonas reinhardtii. We transformed the plastome with a bifunctional transgene encoding an in vivo cleavable fusion polypeptide composed of a hyperthermophilic cellulase and the phosphite dehydrogenase PTXD. The dual use of phosphite as a low-cost, environmentally friendly selective agent and fertilizer afforded axenic algal cultivation via mixotrophic metabolism and efficient expression of the hydrolytic enzyme. This study provides an example of chloroplast genetic engineering in which biosafety is integrated in the sustainable management of microalgal monocultures to produce enzymes with industrial applications.
ABSTRACT Definition of the SubjectAlgae are oxygenic photoautotrophs, offering a very high level ... more ABSTRACT Definition of the SubjectAlgae are oxygenic photoautotrophs, offering a very high level of biodiversity and thus suitable for different practical applications. Today, they are mainly cultivated for human/animal food or to extract high-value chemicals and pharmaceuticals. However, their exploitation could be extended. Algae are attractive as high yield biomass producers, because of the short life cycle, the ability to grow up to very high cell densities, and the easy large-scale cultivation that does not compete with other demands such as those of conventional crops agriculture. Algae can be a resource of renewable, sustainable biofuels. In addition, they can be transformed into “cell factories” to produce recombinant proteins of interest for pharmaceutical companies.IntroductionAlgae are described as “lower” plants that never have true stems, roots, and leaves, and grow photoautotrophically by performing oxygenic photos ...
We demonstrate an ultrabroadband two-dimensional electronic spectrometer that maps energy flow ac... more We demonstrate an ultrabroadband two-dimensional electronic spectrometer that maps energy flow across the visible range. This apparatus enables observation of previously unexplored carotenoid-mediated light-harvesting dynamics in plants, including identification of a debated carotenoid dark state.
This book introduces the basic physical, chemical, and biological principles underlying the first... more This book introduces the basic physical, chemical, and biological principles underlying the first steps in photosynthesis: light absorption, excitation energy transfer, and charge separation. In Part 1, we introduce pigments and their spectroscopic/ redox properties. In Part 2, pigment-proteins as they occur in various natural systems (plants, algae, photosynthetic bacteria) are described, including the regulation of light harvesting. Part 3 deals with the physics underlying light harvesting: energy transfer and electron transport. Part 4 introduces basic and advanced spectroscopic methods, including data analysis. In Part 5, we discuss artificial and natural photosynthetic systems, how they are assembled, and what the energy transfer properties are
Green plants prevent photodamage under high light conditions by dissipating excess energy as heat... more Green plants prevent photodamage under high light conditions by dissipating excess energy as heat. Conformational changes of the photosynthetic antenna complexes activate dissipation by leveraging the sensitivity of the photophysics of the chlorophyll and carotenoids to their surrounding protein. However, the mechanisms and site of dissipation are still debated, largely due to two challenges. First, experiments have been performed in detergent, which can induce non-native conformations, or in vivo, where contributions from the multiple complexes cannot be disentangled and are further obfuscated by laser-induced artifacts. Second, because of the ultrafast timescales and large energy gaps involved, measurements lacked the temporal or spectral requirements. Here, we overcome both challenges by applying ultrabroadband two-dimensional electronic spectroscopy to the principal antenna complex, light-harvesting complex II, in a near-native membrane. The spectra show that the membrane enhanc...
Green plants prevent photodamage under high light conditions by dissipating excess energy as heat... more Green plants prevent photodamage under high light conditions by dissipating excess energy as heat. Conformational changes of the photosynthetic antenna complexes activate dissipation by leveraging the sensitivity of the photophysics of the chlorophyll and carotenoids to their surrounding protein. However, the mechanisms and site of dissipation are still debated, largely due to two challenges. First, because of the ultrafast timescales and large energy gaps involved, measurements lacked the temporal or spectral requirements. Second, experiments have been performed in detergent, which can induce non-native conformations, or in vivo, where contributions from the multiple complexes cannot be disentangled and are further obfuscated by laser-induced artifacts. Here, we overcome both challenges by applying ultrabroadband two-dimensional electronic spectroscopy to the principal antenna complex, light-harvesting complex II, in a near-native membrane. The membrane enhances two dissipative pat...
Proceedings of the National Academy of Sciences, 2019
Significance Protein flexibility is essential for the robustness of biological systems, yet the d... more Significance Protein flexibility is essential for the robustness of biological systems, yet the dynamics underlying this flexibility are difficult to observe, because they are small, fast, and stochastic. Photoprotection in plants is critical for robust growth under highly variable sunlight, but the complexity of photosynthetic proteins means that identifying conformational states and dynamics responsible is challenging. Here, we develop a method using the correlation function of the fluorescence lifetime to characterize multiple dynamical processes in single proteins. By applying this method to the protein Light-Harvesting Complex Stress Related 1 (LHCSR1), we identify two local protein motions that control quenching of excess sunlight, which is a photoprotective effect. Our analytical approach enables a structure-based understanding of the photoprotective mechanisms in green plants.
We utilise ultrabroadband two-dimensional electronic spectroscopy to map out pathways of energy f... more We utilise ultrabroadband two-dimensional electronic spectroscopy to map out pathways of energy flow in LHCII across the entire visible region. In addition to the well-established, low-lying chlorophyll Qy bands, our results reveal additional pathways of energy relaxation on the higher-lying excited states involving the S2 energy levels of carotenoids, including ultrafast carotenoid-to-chlorophyll energy transfer on 90-150 fs timescales.
Marine diatoms are prominent phytoplankton organisms, optimally performing photosynthesis in extr... more Marine diatoms are prominent phytoplankton organisms, optimally performing photosynthesis in extremely variable environments. Diatoms possess a strong ability to dissipate excess absorbed energy as heat via non-photochemical quenching (NPQ). This process relies on changes in carotenoid pigment composition (xanthophyll cycle) and on specific members of the light-harvesting complex (LHC) family specialized in photoprotection (LHCX), which potentially act as NPQ effectors. However, the link between light stress, NPQ, and the existence of different LHCX isoforms is not understood in these organisms. Using picosecond fluorescence analysis, we observed two types of NPQ in the pennate diatom Phaeodactylum tricornutum, depending on light conditions. Short exposure of low-light acclimated cells to high light triggers the onset of energy quenching close to the core of Photosystem II, while prolonged light stress activates NPQ in the antenna. Biochemical analysis indicates a link between the c...
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Papers by Roberto Bassi