tailieunhanh - Báo cáo khoa học: NMR investigations of subunit c of the ATP synthase from Propionigenium modestum in chloroform/methanol/water (4 : 4 : 1)

The subunit c from the ATP synthase ofPropionigenium modestumwas studied by NMR in chloroform/methanol/ water (4 : 4 : 1). In this solvent, subunit c consists of two helical segments, comprisedof residuesL5 to I26andG29 to N82, respectively. On comparing the secondary structure of subunit c fromP. modestumin the organic solvent mixture with that in dodecylsulfate micelles several deviations became apparent: in the organic solvent, the interruption of theahelical structure within the conserved GXGXGXGX motifwas shortened from®ve to tworesidues, . | Eur. J. Biochem. 269 1942-1946 2002 FEBS 2002 doi NMR investigations of subunit c of the ATP synthase from Propionigenium modestum in chloroform methanol water 4 4 1 Ulrich Matthey1 Daniel Braun2 and Peter Dimroth1 1Institut fur Mikrobiologie and 2Institut fur Molekularbiologie und Biophysik Eidgenossische Technische Hochschule Zurich Switzerland The subunit c from the ATP synthase of Propionigenium modestum was studied by NMR in chloroform methanol water 4 4 1 . In this solvent subunit c consists of two helical segments comprised of residues L5 to I26 and G29 to N82 respectively. On comparing the secondary structure of subunit c from P. modestum in the organic solvent mixture with that in dodecylsulfate micelles several deviations became apparent in the organic solvent the interruption of the a helical structure within the conserved GXGXGXGX motif was shortened from five to two residues the prominent interruption of the a helical structure in the cystoplasmic loop region was not apparent and neither was there a break in the a helix after the sodium ion-binding Glu65 residue. The folding of subunit c of P. modestum in the organic solvent also deviated from that of Escherichia coli in the same environment the most important difference being that subunit c of P. modestum did not adopt a stable hairpin structure like subunit c of E. coli. Keywords ATP synthase stable isotope labeling NMR spectroscopy Propionigenium modestum subunit c. F1F0 ATP synthases catalyse the formation of ATP from ADP and inorganic phosphate that is driven by an electrochemical gradient of protons or in some cases Na ions. Similar enzymes are found in chloroplast mitochondria and bacteria. They consist of a cytoplasmic F1 part with the subunit composition a3p3yỗE and a membrane intrinsic F0 moiety which in bacteria has the subunit composition ab2cx. The mechanism for ATP synthesis proposed to involve binding changes of the three catalytic binding sites on the b

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