Escherichia coli cytosol

Shen, Y., Berger, S.J., Smith, R.D. (2001). High-efficiency capillary isoelectric focusing of protein complexes from Escherichia coli cytosolic extracts. J. Chromatogr. A 914,257-264. 

Recently, a potential cytosolic component of the MEP precursor pathway, xylulose kinase, has been cloned and tested for function in an Escherichia coli complementation system. " The kinase activates exogenous xylulose in the cytoplasm. DXP is the precursor for DXS, which resides in the plastid, suggesting the activated substrate must be transported into the plastid. Another xylulose kinase homologue in Arabidopsis that contains a plastid targeting sequence was not active in the E. coli system, suggesting that it may have some other function in the plastid. Perhaps plant and bacterial tissue cultures may be fed xylulose to condition accumulation of isoprenoid metabolites. 

This hypothesis presumes that early free-living prokaryotes had the enzymatic machinery for oxidative phosphorylation and predicts that their modern prokaryotic descendants must have respiratory chains closely similar to those of modern eukaryotes. They do. Aerobic bacteria carry out NAD-linked electron transfer from substrates to 02, coupled to the phosphorylation of cytosolic ADP. The dehydrogenases are located in the bacterial cytosol and the respiratory chain in the plasma membrane. The electron carriers are similar to some mitochondrial electron carriers (Fig. 19-33). They translocate protons outward across the plasma membrane as electrons are transferred to 02. Bacteria such as Escherichia coli have F0Fi complexes in their plasma membranes the F portion protrudes into the cytosol and catalyzes ATP synthesis from ADP and P, as protons flow back into the cell through the proton channel of F0. 

Fig. 5.1 Primary structures of AspATs from various species. P, C, H, Hu, R and M denote for pig, chicken, hamster, human, rat and mouse, respectively, c and m stand for cytosolic and mitochondrial, respectively. eAspAT and tAspAT denote Escherichia coli AspAT and Thermostable AspAT from Thermophilic Bacilus species19 , respectively. Letters in bold face type represent residues discussed in the text.

Rathinasabapathi, B., Wu, S., Sundaram, S., Rivoal, J., Srivastava, M., and Ma, L.Q. 2006. Arsenic resistance in Pteris vittata L. Identification of a cytosolic triosephosphate isomerase based on cDNA expression cloning in Escherichia coli. Plant Molecular Biology, 62 845-57. 

The primary consideration in the genesis of any biological membrane is the location of the synthetic apparatus that manufactures the subunits of the membrane and its relationship to the final distribution of its products [13], In Escherichia coli, substantial evidence indicates that the synthesis of phospholipids occurs at the inner (cytoplasmic) membrane by enzymes that have their active sites on the cytoplasmic surface of the inner membrane. Such an orientation allows free access of water-soluble substrates and reaction products to the cytosol. 

Pernecky, S.J., J.R. Larson, R.M. Philpot, and M.J. Coon (1993). Expression of truncated forms of liver microsomal P450 cytochromes 2B4 and 2E1 in Escherichia coli. Influence of NH2-terminal region on localization in cytosol and membranes. Proc. Natl. Acad. Sci. USA 90, 2651-2655. 

An extensive comparison between these two gradient modes in lEX-RP separation of cytosolic proteins from Escherichia coli revealed a more effective fractionation for a linear salt gradient [70]. Fewer major proteins were distributed to multiple second-dimension fractions. 

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