title: Metabolic adaptation in transplastomic plants massively accumulating recombinant proteins.
abstract: BACKGROUND
  Recombinant chloroplasts are endowed with an astonishing capacity to accumulate foreign proteins. However, knowledge about the impact on resident proteins of such high levels of recombinant protein accumulation is lacking.
  
  
  RESULTS
  Here we used proteomics to characterize tobacco (Nicotiana tabacum) plastid transformants massively accumulating a p-hydroxyphenyl pyruvate dioxygenase (HPPD) or a green fluorescent protein (GFP). While under the conditions used no obvious modifications in plant phenotype could be observed, these proteins accumulated to even higher levels than ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), the most abundant protein on the planet. This accumulation occurred at the expense of a limited number of leaf proteins including Rubisco. In particular, enzymes involved in CO(2) metabolism such as nuclear-encoded plastidial Calvin cycle enzymes and mitochondrial glycine decarboxylase were found to adjust their accumulation level to these novel physiological conditions.
  
  
  CONCLUSIONS
  The results document how protein synthetic capacity is limited in plant cells. They may provide new avenues to evaluate possible bottlenecks in recombinant protein technology and to maintain plant fitness in future studies aiming at producing recombinant proteins of interest through chloroplast transformation.
authors.affiliation: Centre National de la Recherche Scientifique-Bayer CropScience Joint Laboratory, UMR5240, Lyon, France. julia.bally@sydney.edu.au
authors.forename: Julia
authors.initials: J
authors.lastname: Bally
authors.forename: Claudette
authors.initials: C
authors.lastname: Job
authors.forename: Maya
authors.initials: M
authors.lastname: Belghazi
authors.forename: Dominique
authors.initials: D
authors.lastname: Job
mesh_terms: D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018087:Plastids / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D012273:Ribulose-Bisphosphate Carboxylase