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Query: UNIPROT:P06889 (Mol)
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Coriaria, which has the most conspicuously disjunct distribution of the flowering plants, is distributed in four separate areas of the world. The phylogenetic relationships of 12 Coriaria species collected from the representative disjunct areas were inferred by comparing 2416 bp of the combined data set of rbcL (a large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase) and matK (maturase K) genes. The phylogenetic tree shows that the Chile-Papua New Guinea-New Zealand-Pacific islands species and the Central America-northern South America species form a sister group, and the Eurasian clade is more basal to them. The divergence time between the Eurasian group and the other species was estimated as 63 or 59 million years ago using rbcL and matK molecular clocks, respectively. These results do not support previously proposed hypotheses which explain the disjunct distribution on the basis of continental drift but suggest that the distribution pattern was formed by several geographical migrations and separations in the Cenozoic.
Mol Phylogenet Evol 2000 Jan
PMID:Molecular phylogeny of Coriaria, with special emphasis on the disjunct distribution. 1063 Oct 39

The small subunit of ribulose-bisphosphate carboxylase (Rubisco), encoded by rbcS, is essential for photosynthesis in both C3 and C4 plants, even though the cell specificity of rbcS expression is different between C3 and C4 plants. The C3 rbcS is specifically expressed in mesophyll cells, while the C4 rbcS is expressed in bundle sheath cells, and not mesophyll cells. Two chimeric genes were constructed consisting of the structural gene encoding beta-glucuronidase (GUS) controlled by the two promoters from maize (C4) and rice (C3) rbcS genes. These constructs were introduced into a C4 plant, maize. Both chimeric genes were specifically expressed in photosynthetic organs, such as leaf blade, but not in non-photosynthetic organs. The expressions of the genes were also regulated by light. However, the rice promoter drove the GUS activity mainly in mesophyll cells and relatively low in bundle sheath cells, while the maize rbcS promoter induced the activity specifically in bundle sheath cells. These results suggest that the rice promoter contains some cis-acting elements responding in an organ-specific and light-inducible regulation manner in maize but does not contain element(s) for bundle sheath cell-specific expression, while the maize promoter does contain such element(s). Based on this result, we discuss the similarities and differences between the rice (C3) and maize (C4) rbcS promoter in terms of the evolution of the C4 photosynthetic gene.
Plant Mol Biol 2000 Sep
PMID:The promoter of rbcS in a C3 plant (rice) directs organ-specific, light-dependent expression in a C4 plant (maize), but does not confer bundle sheath cell-specific expression. 1109 84

The N-terminal transit peptide of chloroplast proteins is necessary and sufficient to direct proteins to the chloroplasts. However, the requirement of the transit peptide of chloroplast proteins is not fully understood. In this study we investigated the requirement of a transit peptide at the level of amino acid sequence using an in vivo targeting approach. Targeting experiments with green fluorescent protein (GFP) fusion proteins containing varying lengths of the N-terminal region of the small subunit of rubisco complex (RbcS) revealed that at least 73 amino acid residues of the N-terminal region is required to direct GFP to the chloroplasts without affecting the efficiency. Even a small deletion from the C- or N-termini of the minimal length of the transit peptide results in strong inhibition of targeting. Also, a small internal deletion within the minimal transit peptide strongly affected targeting of GFP fusion proteins. However, when we replaced one or two amino acid residues of the transit peptide with corresponding numbers of alanine residues sequentially, all the mutants were imported into chloroplasts with 80 to 100% efficiency. Together these results suggest that the overall context of amino acid sequence, but not any specific amino acid residue, of the transit peptide is critical for targeting to the chloroplasts.
Mol Cells 2002 Dec 31
PMID:In vivo import experiments in protoplasts reveal the importance of the overall context but not specific amino acid residues of the transit peptide during import into chloroplasts. 1252 2

A bacterial thermostable cellulase, the endo-1,4-beta-D-glucanase E1 from Acidothermus cellulolyticus, was imported into chloroplasts, and an active enzyme was recovered both in vitro and in vivo. Precursor fusion proteins were synthesized with E1 or its catalytic domain, CD, fused to the transit peptide of ferredoxin or ribulose-bisphosphate carboxylase activase for stromal targeting. A spacer region of 1, 5 or 15 amino acids was included carboxy to the transit peptide. The efficiency of import and processing by the stromal processing peptidase depended on the nature of the transit peptide and the passenger protein, and increased with the length of the spacer between them. Besides finding E1 or CD in the stroma, protein was arrested in the envelope during import showing that structural features of E1 and CD, along with their proximity to the transit peptide, influence translocation. The cellulose binding domain and/or serine/proline/threoline-rich linker of E1 may impede efficient import. Significantly, most precursors for E1 and CD synthesized by in vitro translation possessed endoglucanse activity that was temperature-dependent, and required the residues AGGGY at the N-terminus of E1 and CD. Furthermore, activity was detected upon import into chloroplasts. Based on the in vitro analyses, five precursor fusion proteins were selected to determine if E1 and CD would be successfully targeted to chloroplasts in vivo. In transgenic tobacco plants, E1 and CD accumulated in both the stromal and membrane fractions and, importantly, chloroplast extracts showed endoglucanase activity.
Plant Mol Biol 2003 Mar
PMID:Expression and import of an active cellulase from a thermophilic bacterium into the chloroplast both in vitro and in vivo. 1265 Jun 16

A system for biological selection of randomly mutagenized ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) genes from the cyanobacterium Synechococcus PCC6301 was designed in which a Rubisco deletion mutant of the photosynthetic bacterium Rhodobacter capsulatus served as a host. Trans-complementation with the Synechococcus PCC6301 rbcLS genes enabled anaerobic photoautotrophic growth of the R.capsulatus deletion strain with 5% CO(2), but not with 1.5% CO(2) in the atmosphere, and this strain could not grow under aerobic chemoautotrophic conditions. Phenotypic differences between the R.capsulatus host strain complemented with the wild-type rbcLS genes and transconjugates carrying mutated genes were used to identify mutants that were able to complement to photoautotrophic growth with 1.5% CO(2). These "positive" mutant proteins were unaffected for any measured kinetic properties, with a single exception. A mutant with a valine substitution at phenylalanine 342 had an increased affinity for ribulose-1,5-bisphosphate. Mutants with changes in the affinity for CO(2) were isolated through negative selection, in which mutants incapable of complementing R.capsulatus to photoautotrophic growth with 5% CO(2) were identified. Mutations at aspartate 103 resulted in enzymes that were greatly affected for different kinetic parameters, including an increased K(m) for CO(2). This study demonstrated that random mutagenesis and bioselection procedures could be used to identify mutations that influence important properties of bacterial Rubisco; these residues would not have been identified by other methods.
J Mol Biol 2003 Aug 15
PMID:Positive and negative selection of mutant forms of prokaryotic (cyanobacterial) ribulose-1,5-bisphosphate carboxylase/oxygenase. 1289 28

This study investigates the influence of exogenously applied abscisic acid (ABA) on the leaves and leaf sheaths of two-week-old rice seedling at the level of the proteome. Significant differences were observed in the two-dimensional polyacrylamide gel electrophoresis protein profiles between control and ABA treated samples. Amino-acid sequence analysis of affected proteins revealed that ABA caused drastic changes in the major photosynthetic protein, ribulose 1,5-bisphosphate carboxylase/oxygenase and accumulation of certain defense/stress-related proteins. Moreover, cutting or treating leaf sheaths with jasmonic acid (JA) rapidly increased the endogenous level of ABA, suggesting a role for ABA during the defense/stress-response. Comparative study indicated a potential overlap between ABA and JA as detected at the level of the proteome. Furthermore, in vitro protein phosphorylation experiments and in-gel kinase assays also revealed considerable changes in the phosphorylation status of some proteins, and differential effects on myelin basic protein and calcium-dependent protein kinase activities by ABA treatment, which suggests involvement of kinase in the downstream signaling cascade. These results provide evidence at proteome level for the involvement of ABA in stress-response in rice seedling.
Mol Biol Rep 2004 Dec
PMID:Abscisic acid promoted changes in the protein profiles of rice seedling by proteome analysis. 1566 5

Phosphoribulokinase (PRK) is an essential enzyme of photosynthetic eukaryotes which is active in the plastid-located Calvin cycle and regenerates the substrate for ribulose-bisphosphate carboxylase/oxygenase (Rubisco). Rhodophytes and chlorophytes (red and green algae) recruited their nuclear-encoded PRK from the cyanobacterial ancestor of plastids. The plastids of these organisms can be traced back to a single primary endosymbiosis, whereas, for example, haptophytes, dinoflagellates, and euglenophytes obtained their "complex" plastids through secondary endosymbioses, comprising the engulfment of a unicellular red or green alga by a eukaryotic host cell. We have cloned eight new PRK sequences from complex algae as well as a rhodophyte in order to investigate their evolutionary origin. All available PRK sequences were used for phylogenetic analyses and the significance of alternative topologies was estimated by the approximately unbiased test. Our analyses led to several astonishing findings. First, the close relationship of PRK genes of haptophytes, heterokontophytes, cryptophytes, and dinophytes (complex red lineage) supports a monophyletic origin of their sequences and hence their plastids. Second, based on PRK genes the complex red lineage forms a highly supported assemblage together with chlorophytes and land plants, to the exclusion of the rhodophytes. This green affinity is in striking contrast to the expected red algal origin and our analyses suggest that the PRK gene was acquired once via lateral transfer from a green alga. Third, surprisingly the complex green lineages leading to Bigelowiella and Euglena probably also obtained their PRK genes via lateral gene transfers from a red alga and a complex alga with red plastids, respectively.
J Mol Evol 2006 Feb
PMID:A "green" phosphoribulokinase in complex algae with red plastids: evidence for a single secondary endosymbiosis leading to haptophytes, cryptophytes, heterokonts, and dinoflagellates. 1647 87

Carboxysomes are polyhedral bodies consisting of a proteinaceous shell filled with ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO). They are found in the cytoplasm of all cyanobacteria and some chemoautotrophic bacteria. Previous studies of Halothiobacillus neapolitanus and Nitrobacter agilis carboxysomes suggest that the structures are either icosahedral or dodecahedral. To determine the protein shell structure more definitively, purified H. neapolitanus carboxysomes were re-examined by cryo-electron tomography and scanning transmission electron microscopy (STEM). Due to the limited tilt angles in the electron microscope, the tomographic reconstructions are distorted. Corrections were made in the 3D orientation searching and averaging of the computationally extracted carboxysomes to minimize the missing data effects. It was found that H. neapolitanus carboxysomes vary widely in size and mass as shown by cryo-electron tomography and STEM mass measurements, respectively. We have aligned and averaged carboxysomes in several size classes from the 3D tomographic reconstruction by methods that are not model-biased. The averages reveal icosahedral symmetry of the shell, but not of the density inside it, for all the size classes.
J Mol Biol 2006 Dec 01
PMID:Structure of Halothiobacillus neapolitanus carboxysomes by cryo-electron tomography. 1702 23

Roundup Ready soy contains the CP4-enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) protein. Serum IgE from two distinct populations of soy-allergic patients were recruited to determine their IgE-binding specificity. One population consisted of 10 adult patients from Europe, whose primary diagnosis was soy food allergy with some also having mite allergy. In addition, 6 primarily mite-allergic, 6 food-allergic (celery, carrot, milk, shrimp, walnut, and apple), and 5 non-allergic patients were tested. Another population consisted of 13 children from Korea, whose primary diagnosis was atopic dermatitis and secondarily soy and egg sensitization. In addition, 11 non-allergic patients were tested. Each patient population was extensively characterized with respect to clinical symptoms, specific IgE (CAP) scores, and total IgE. Immunoblots and ELISA assays were developed using serum IgE from these patients and soy extracts, CP4 EPSPS, rice extract, ovalbumin, rubisco, purified major peanut allergen Ara h 2, the putative soy allergen Gly m Bd 30k and mite allergen Der f 2 proteins as the intended targets. Immunoblot results indicated that soy-allergic patients bound soy extracts but did not specifically bind rubisco or CP4 EPSPS. ELISA results were in general agreement with the immunoblot results except that rubisco bound significant quantities of serum IgE from some patients. These results indicate that the CP4 EPSPS protein does not bind significant quantities of IgE from two geographically distinct sensitive populations and there is no evidence for an increased allergenic potential of this biotech protein.
Mol Nutr Food Res 2007 Aug
PMID:Serum testing of genetically modified soybeans with special emphasis on potential allergenicity of the heterologous protein CP4 EPSPS. 1763 14

Carboxysomes are organelle-like polyhedral bodies found in cyanobacteria and many chemoautotrophic bacteria that are thought to facilitate carbon fixation. Carboxysomes are bounded by a proteinaceous outer shell and filled with ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the first enzyme in the CO(2) fixation pathway, but exactly how they enhance carbon fixation is unclear. Here we report the three-dimensional structure of purified carboxysomes from Synechococcus species strain WH8102 as revealed by electron cryotomography. We found that while the sizes of individual carboxysomes in this organism varied from 114 nm to 137 nm, surprisingly, all were approximately icosahedral. There were on average approximately 250 RuBisCOs per carboxysome, organized into three to four concentric layers. Some models of carboxysome function depend on specific contacts between individual RuBisCOs and the shell, but no evidence of such contacts was found: no systematic patterns of connecting densities or RuBisCO positions against the shell's presumed hexagonal lattice could be discerned, and simulations showed that packing forces alone could account for the layered organization of RuBisCOs.
J Mol Biol 2007 Sep 21
PMID:The structure of isolated Synechococcus strain WH8102 carboxysomes as revealed by electron cryotomography. 1766 19


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