1a91: Difference between revisions

[[Image:1a91.gif|left|200px]]<br /><applet load="1a91" size="350" color="white" frame="true" align="right" spinBox="true"  

Subunit c is the H+-translocating component of the F1F0 ATP synthase complex. H+ transport is coupled to conformational changes that ultimately lead to ATP synthesis by the enzyme. The properties of the monomeric subunit in a single-phase solution of chloroform-methanol-water (4:4:1) have been shown to mimic those of the protein in the native complex. Triple resonance NMR experiments were used to determine the complete structure of monomeric subunit c in this solvent mixture. The structure of the protein was defined by &gt;2000 interproton distances, 64 (3)JN alpha, and 43 hydrogen-bonding NMR-derived restraints. The root mean squared deviation for the backbone atoms of the two transmembrane helices was 0.63 A. The protein folds as a hairpin of two antiparallel helical segments, connected by a short structured loop. The conserved Arg41-Gln42-Pro43 form the top of this loop. The essential H+-transporting Asp61 residue is located at a slight break in the middle of the C-terminal helix, just prior to Pro64. The C-terminal helix changes direction by 30 +/- 5 degrees at the conserved Pro64. In its protonated form, the Asp61 lies in a cavity created by the absence of side chains at Gly23 and Gly27 in the N-terminal helix. The shape and charge distribution of the molecular surface of the monomeric protein suggest a packing arrangement for the oligomeric protein in the F0 complex, with the front face of one monomer packing favorably against the back face of a second monomer. The packing suggests that the proton (cation) binding site lies between packed pairs of adjacent subunit c.

1A91 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/H(+)-transporting_two-sector_ATPase H(+)-transporting two-sector ATPase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.6.3.14 3.6.3.14] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A91 OCA].  

[[Category: Fillingame, R H.]]

[[Category: Girvin, M E.]]

[[Category: Markley, J L.]]

[[Category: Rastogi, V K.]]

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