Bacterial gene transfer by natural genetic transformation in the environment.

summary The gradual but huge increase in atmospheric O # concentration that followed the evolution of oxygenic photosynthesis is one consequence that marks this event as one of the most significant in the earth’s history. The high redox potential of the O # }water couple makes it an extremely powerful electron sink that enables energy to be transduced in respiration. In addition to the tetravalent interconversion of O # and water, there exist a plethora of reactions that involve the partial reduction of O # or photodynamic energy transfer to produce active oxygen species (AOS). All these redox reactions have become integrated during evolution into the aerobic photosynthetic cell. This review considers photosynthesis as a whole-cell process, in which O # and AOS are involved in reactions at both photosystems, enzyme regulation in the chloroplast stroma, photorespiration, and mitochondrial electron transport in the light. In addition, oxidants and antioxidants are discussed as metabolic indicators of redox status, acting as sensors and signal molecules leading to acclimatory responses. Our aim throughout is to assess the insights gained from the application of mutagenesis and transformation techniques to studies of the role of O # and related redox components in the integrated regulation of photosynthesis.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1469-8137.2000.00667.x

Tansley Review No. 112

■ Abstract Ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) catalyzes the first step in net photosynthetic CO2 assimilation and photorespiratory carbon oxidation. The enzyme is notoriously inefficient as a catalyst for the carboxylation of RuBP and is subject to competitive inhibition by O2, inactivation by loss of carbamylation, and dead-end inhibition by RuBP. These inadequacies make Rubisco rate limiting for photosynthesis and an obvious target for increasing agricultural productivity. Resolution of X-ray crystal structures and detailed analysis of divergent, mutant, and hybrid enzymes have increased our insight into the structure/function relationships of Rubisco. The interactions and associations relatively far from the Rubisco active site, including regulatory interactions with Rubisco activase, may present new approaches and strategies for understanding and ultimately improving this complex enzyme.

RUBISCO: Structure, Regulatory Interactions, and Possibilities for a Better Enzyme

Ecosystem simulation models use descriptive input parameters to establish the physiology, biochemistry, structure, and allocation patterns of vegetation functional types, or biomes. For single-stand simulations it is possible to measure required data, but as spatial resolution increases, so too does data unavailability. Generalized biome parameterizations are then required. Undocumented parameter selection and unknown model sensitivity to parameter variation for larger-resolution simulations are currently the major limitations to global and regional modeling. The authors present documented input parameters for a process-based ecosystem simulation model, BIOME–BGC, for major natural temperate biomes. Parameter groups include the following: turnover and mortality; allocation; carbon to nitrogen ratios (C:N); the percent of plant material in labile, cellulose, and lignin pools; leaf morphology; leaf conductance rates and limitations; canopy water interception and light extinction; and the percent of...

/pdf/parameterization-and-sensitivity-analysis-of-the-biome-bgc-1uc4yj1399.pdf

Parameterization and Sensitivity Analysis of the BIOME–BGC Terrestrial Ecosystem Model: Net Primary Production Controls

INTRODUCTION 379 Role in Photosynthesis 379 Enzyme Reaction 380 MOLECULAR PROPERTIES .... . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . ... . . . .. 381 Native Enzyme 381 Subunit Structure 382 Is Bound Capper Involved? 384 CATALYTIC PROPERTIES .... . ..... 384 Identification of Enzyme Activation 384 Oxygenase Activity 388 Relationship Between Carboxylase and Oxygenase 389 Kinetics of the Activated Enzyme ........ 390 Proper Assay of Fully Activated Enzyme ... ..... . ... 393 SUMMARY OF KINETIC PARAMETERS ........ . . . ... . . . . ... 393 CONCLUSIONS ... .. . ....... .. . .. ..... . .. .. . .. .. . . . . . . .. . . .. ... ... . .. . . . . . . ... . .. . . . . .. . . ....... 394 Physiological Control of CO2 Fixation in the Chloroplast 394 Future Research Aspects 395

Ribulose 1,5-Bisphosphate Carboxylase-Oxygenase

Novel chimeric constructions and methods for their use are provided for expression of exogenous genes in a plant chloroplast. Particularly, expression is achieved by the use of a chloroplast or bacterial 5′ untranslated region in the expression cassette. The expression cassette may be integrated into the chloroplast genome by the use of chloroplast DNA flanking sequences, or may replicate autonomously if provided with a chloroplast origin of replication. Plants and cells containing the transformed chloroplasts are also provided. The constructs may be used with both monocotyledenous and dicotyledenous chloroplasts.

/pdf/genetic-engineering-of-plant-chloroplasts-2pam7uud9h.pdf

Genetic engineering of plant chloroplasts

d-Ribulose 1,5-Diphosphate Carboxylase from Rhodospirillum rubrum: II. QUATERNARY STRUCTURE, COMPOSITION, CATALYTIC, AND IMMUNOLOGICAL PROPERTIES

d-Ribulose 1,5-Diphosphate Carboxylase from Rhodospirillum rubrum I. LEVELS, PURIFICATION, AND EFFECTS OF METALLIC IONS

Mechanism of action of isocitrate lyase from Pseudomonas indigofera.

Article de synthese sur l'isocitrate lyase, isolement, comparaison des techniques de purification, etude de sa structure, de sa specificite, de sa stabilite et analyse cinetique

Bruce A. McFadden

Papers

Genetic engineering of plant chloroplasts

d-Ribulose 1,5-Diphosphate Carboxylase from Rhodospirillum rubrum: II. QUATERNARY STRUCTURE, COMPOSITION, CATALYTIC, AND IMMUNOLOGICAL PROPERTIES

d-Ribulose 1,5-Diphosphate Carboxylase from Rhodospirillum rubrum I. LEVELS, PURIFICATION, AND EFFECTS OF METALLIC IONS

Mechanism of action of isocitrate lyase from Pseudomonas indigofera.

Comparative structure, function and regulation of isocitrate lyase, an important assimilatory enzyme.