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ABSTRACT: The structure of the C-terminus of subunit E (E(101-206)) of Methanocaldococcus jannaschii A-ATP synthase was determined at 4.1 A. E(101-206) consist of a N-terminal globular domain with three alpha-helices and four antiparallel beta-strands and an alpha-helix at the very C-terminus. Comparison of M. jannaschii E(101-206) with the C-terminus E(81-198) subunit E from Pyrococcus horikoshii OT3 revealed that the kink in the C-terminal alpha-helix of E(81-198), involved in dimer formation, is absent in M. jannaschii E(101-206). Whereas a major dimeric surface interface is present between the P. horikoshii E(81-198) molecules in the asymmetric unit, no such interaction could be found in the M. jannaschii E(101-206) molecules. To verify the oligomeric behaviour, the low resolution structure of the recombinant E(85-206) from M. jannaschii was determined using small angle X-ray scattering. Rigid body modeling of two copies of one of the monomer established a fit with a tail to tail arrangement.
Journal of Bioenergetics 08/2010; 42(4):311-20. · 2.81 Impact Factor
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ABSTRACT: The H subunit of the A1AO ATP synthase is a component of one of the peripheral stalks connecting the A1 and AO domain. Subunit H of the Methanocaldococcus jannaschii A1AO ATP synthase was analyzed by small-angle X-ray scattering (SAXS) in order to determine the first low-resolution structure of this molecule in solution. Independent to the concentration used, the protein is dimeric and has a boomerang-like shape, divided into two arms of 12.0 and 6.8 nm in length. Circular dichroism (CD) spectroscopy revealed that subunit H is comprised of 78% alpha-helix and a coiled-coil arrangement. To understand the orientation of the helices and the localization of the N- and C-termini inside the dimer, three truncated forms of subunit H (H8-104, H1-98, and H8-98) were expressed, purified, and analyzed by CD. SAXS experiments of H1-98 show that the maximum dimension of the truncated protein dropped to 15.1 nm. Comparison of the low-resolution shapes of H and H1-98 indicates that this goes along with structural changes in the C-terminal arm of the boomerang-like structure. Together with the result of a disulfide formation of a fourth truncated form, H1-47, with a cysteine at position 47, the data suggest a parallel alpha-helical interaction. In addition, all four truncated proteins are dimeric in solution. Tryptophan emission spectra showed specific binding of H and H8-104 to the neighboring, catalytic A subunit, which could not be detected in the presence of H1-98. Finally, the arrangement of H within the A1AO ATP synthase is presented.
Biochemistry 03/2007; 46(8):2070-8. · 3.42 Impact Factor
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ABSTRACT: The first low-resolution shape of subunit F of the A(1)A(O) ATP synthase from the archaeon Methanosarcina mazei Gö1 in solution was determined by small angle X-ray scattering. Independent to the concentration used, the protein is monomeric and has an elongated shape, divided in a main globular part with a length of about 4.5 nm, and a hook-like domain of about 3.0 nm in length. The subunit-subunit interaction of subunit F inside the A(1)A(O) ATP synthase in the presence of 1-ethyl-3-(dimethylaminopropyl)-carbodiimide EDC was studied as a function of nucleotide binding, demonstrating movements of subunits F relative to the nucleotide-binding subunit B. Furthermore, in the intact A(1)A(O) complex, crosslinking of subunits D-E, A-H and A-B-D was obtained and the peptides, involved, were analyzed by MALDI-TOF mass spectrometry. Based on these data the surface of contact of B-F could be mapped in the high-resolution structure of subunit B of the A(1)A(O) ATP synthase.
Journal of Bioenergetics 05/2006; 38(2):83-92. · 2.81 Impact Factor
