Publications by authors named "Robert J Dimario"

Plants have many genes encoding both alpha and beta type carbonic anhydrases. Arabidopsis has eight alpha type and six beta type carbonic anhydrase genes. Individual carbonic anhydrases are localized to specific compartments within the plant cell.

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  • The study investigates the two PEPC genes in two C4 grasses, Panicum miliaceum and Echinochloa colona, which typically possess one highly expressed PEPC gene that facilitates the carbon-concentrating mechanism in C4 photosynthesis.
  • Researchers synthesized coding sequences for the PEPC proteins from both grasses, performed point mutations, and analyzed their kinetic properties using advanced techniques.
  • Results showed that PEPCs in P. miliaceum were highly similar and had similar kinetic properties, whereas the PEPCs in E. colona had notable differences, particularly in how they responded to allosteric regulators, suggesting evolutionary variations.
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Carbonic anhydrases (CAs) are zinc-metalloenzymes that catalyze the interconversion of CO2 and HCO3-. In heterotrophic organisms, CAs provide HCO3- for metabolic pathways requiring a carboxylation step. Arabidopsis (Arabidopsis thaliana) has 14 α- and β-type CAs, two of which are plastid CAs designated as βCA1 and βCA5.

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Mesophyll CO conductance (g ) in C species responds to short-term (minutes) changes in environment potentially due to changes in leaf anatomical and biochemical properties and measurement artefacts. Compared with C species, there is less information on g responses to short-term changes in environmental conditions such as partial pressure of CO (pCO ) across diverse C species and the potential determinants of these responses. Using 16 C grasses we investigated the response of g to short-term changes in pCO and its relationship with leaf anatomy and biochemistry.

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In recent years, researchers have attempted to improve photosynthesis by introducing components from cyanobacterial and algal CO2-concentrating mechanisms (CCMs) into terrestrial C3 plants. For these attempts to succeed, we need to understand the CCM components in more detail, especially carbonic anhydrase (CA) and bicarbonate (HCO3−) transporters. Heterologous complementation systems capable of detecting carbonic anhydrase activity (i.

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  • Carbonic anhydrase (CA) plays a crucial role in C4 photosynthesis by converting dissolved CO into bicarbonate, which is then used in the carbon-concentrating mechanism (CCM).
  • A study found that maize plants lacking two main types of CA (ca1ca2 double mutant) had significantly reduced CA activity but showed little difference in growth under normal CO levels, suggesting other factors might compensate.
  • Further experiments removing a third CA (CA8) from these plants led to almost complete loss of CA activity, resulting in poor photosynthetic performance and dependence on higher CO levels, indicating insufficient CA activity for effective C4 CCM function.
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  • The enzyme phosphoenolpyruvate carboxylase (PEPC) plays a crucial role in initiating photosynthesis and driving the carbon-concentrating mechanism (CCM) in C plants, particularly under conditions of limited carbon availability.
  • Variation in bicarbonate affinity (K) among different C plant species is influenced by specific amino acid changes in PEPC, which can affect photosynthesis rates during drought conditions.
  • Research on 20 C grasses revealed a significant range of K values, demonstrating the potential for molecular engineering to enhance PEPC affinity and improve carbon photosynthetic efficiency in important C crops.
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Phosphoenolpyruvate (PEP) carboxylase (PEPc) catalyzes the first committed step of C4 photosynthesis generating oxaloacetate from bicarbonate (HCO3-) and PEP. It is hypothesized that PEPc affinity for HCO3- has undergone selective pressure for a lower KHCO3 (Km for HCO3-) to increase the carbon flux entering the C4 cycle, particularly during conditions that limit CO2 availability. However, the decrease in KHCO3 has been hypothesized to cause an unavoidable increase in KPEP (Km for PEP).

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Carbonic anhydrases (CAs) are enzymes that catalyze the interconversion of CO and HCO. In nature, there are multiple families of CA, designated with the Greek letters α through θ. CAs are ubiquitous in plants, algae and photosynthetic bacteria, often playing essential roles in the CO concentrating mechanisms (CCMs) which enhance the delivery of CO to Rubisco.

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Carbonic anhydrases (CAs) are zinc metalloenzymes that catalyze the interconversion of CO and HCO and are ubiquitous in nature. Higher plants contain three evolutionarily distinct CA families, αCAs, βCAs, and γCAs, where each family is represented by multiple isoforms in all species. Alternative splicing of CA transcripts appears common; consequently, the number of functional CA isoforms in a species may exceed the number of genes.

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Carbonic anhydrases (CAs) are zinc metalloenzymes that interconvert CO2 and HCO3 (-) In plants, both α- and β-type CAs are present. We hypothesize that cytoplasmic βCAs are required to modulate inorganic carbon forms needed in leaf cells for carbon-requiring reactions such as photosynthesis and amino acid biosynthesis. In this report, we present evidence that βCA2 and βCA4 are the two most abundant cytoplasmic CAs in Arabidopsis (Arabidopsis thaliana) leaves.

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This review presents an overview of the two ways that cyanobacteria, algae, and plants have adapted to high O2 and low CO2 concentrations in the environment. First, the process of photorespiration enables photosynthetic organisms to recycle phosphoglycolate formed by the oxygenase reaction catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Second, there are a number of carbon concentrating mechanisms that increase the CO2 concentration around Rubisco which increases the carboxylase reaction enhancing CO2 fixation.

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Aquatic photosynthetic organisms, such as the green alga Chlamydomonas reinhardtii, respond to low CO(2) conditions by inducing a CO(2) concentrating mechanism (CCM). Carbonic anhydrases (CAs) are important components of the CCM. CAs are zinc-containing metalloenzymes that catalyze the reversible interconversion of CO(2) and HCO(3)(-).

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