C.S., cross section; L.S., longitudinal section. (TIF) Bacterial strains and plasmids used in this study. (DOC) The gene ontology distribution of differentially expressed genes in the transketolase I-overexpressing strain ofR. metabolism were enriched in the transketolase II over-expressed strain. Furthermore, ATP synthesis assays showed a significant increase in ATP synthesis in the transketolase II over-expressed strain. A PEPCK activity assay showed that PEPCK activity was higher Pargyline hydrochloride in transketolase over-expressed strains than in the unfavorable control strain. == Conclusions/Significance == Taken together, our results indicate that the two isoforms of transketolase inR. palustriscould affect photoautotrophic growth through both common and divergent metabolic mechanisms. == Introduction == Systems biology is usually a relatively new field that aims at a system-level understanding of biological systems. Recent progress in the field of molecular biology has enabled enormous amounts of data to be obtained[1]and, with the introduction of high-throughput proteomics and microarray technologies, the study of systems biology has become Pargyline hydrochloride possible[2],[3]. The microarray technique is usually a powerful, high-throughput, functional genomics method for accurately determining changes in global gene expression[4],[5]. In proteomics, powerful high-throughput methods allow the study of the complete set of proteins (the proteome) that are expressed at a given time in a cell, tissue, organ or organism[6]. Rhodopseudomonas palustris(R. palustris) is a purple nonsulfur anoxygenic phototrophic bacterium that belongs to the -proteobacteria class. It is a common soil and water bacterium that lives by converting sunlight to energy and by absorbing atmospheric carbon dioxide and converting it to biomass[7][10]. The availability of the complete annotated genome sequence ofR. palustrisand the shotgun proteomics data of four different metabolic pathways serves as a powerful platform for more detailed systems biology characterizations[8],[11]. Photoautotrophism is one of the major pathways by which autotrophic bacteria assimilate CO2. In photoautotrophic conditions, the organic carbon source that is necessary to sustain metabolic requirements in autotrophic organisms can be synthesized from inorganic carbon sources through CO2fixation. In most autotrophic bacteria, the Calvin-Benson-Bassham (CBB) reductive pentose phosphate cycle is the main route for CO2assimilation. Under photoautotrophic conditions, photosynthesis is used as an energy generating mechanism in the CBB cycle, which not only allows the bacteria to meet their demand for carbon but also balances their redox status[12][16]. When facing higher redox pressures, the CBB cycle can function as an electron sink with CO2as an electron acceptor[17]. Consequently, CO2fixation and reduction are substantially enhanced to enable the consumption of Rabbit polyclonal to Amyloid beta A4.APP a cell surface receptor that influences neurite growth, neuronal adhesion and axonogenesis.Cleaved by secretases to form a number of peptides, some of which bind to the acetyltransferase complex Fe65/TIP60 to promote transcriptional activation.The A excess or accumulated reducing equivalents[18],[19]. The proteins within the CBB cycle include transketolase I (cbbT1), transketolase II (cbbT2), phosphoribulokinase (cbbP), fructose-1,6-bisphosphate aldolase (cbbA), ribulose 1,5-bisphosphate carboxylase/oxygenase (cbbLS) and D-fructose 1,6-bisphosphatase (cbbF). Cyanobacteria have been used as the model by which to study the regulation of the catalytic enzymes involved in the Calvin cycle, with genetic architectural techniques used to enhance photosynthetic yield and growth[20]. Some studies have indicated that exogenous expression of some of these catalytic enzymes, such as cbbA and cbbF, significantly improves photosynthetic capacity and growth[20][22]. However, studies of transketolase I and Pargyline hydrochloride transketolase II in anaerobic photoautotrophic bacteria have yielded inconclusive results. Transketolase, a key enzyme involved in the reductive CBB cycle and non-oxidative part of the pentose phosphate pathway, plays a critical role in connecting the pentose phosphate pathway to glycolytic intermediates[23],[24]. In various organisms, including bacteria, plants and.