Domain features of the peripheral stalk subunit H of the methanogenic A1AO ATP synthase and the NMR solution structure of H(1-47).
A series of truncated forms of subunit H were generated to establish the domain features of that protein. Circular dichroism analysis demonstrated that H is divided at least into a C-terminal coiled-coil domain within residues 54-104, and an N-terminal domain formed by adjacent alpha-helices. With a cysteine at the C-terminus of each of the truncated proteins (H(1-47), H(1-54), H(1-59), H(1-61), H(1-67), H(1-69), H(1-71), H(1-78), H(1-80), H(1-91), and H(47-105)), the residues involved in formation of the coiled-coil interface were determined. Proteins H(1-54), H(1-61), H(1-69), and H(1-80) showed strong cross-link formation, which was weaker in H(1-47), H(1-59), H(1-71), and H(1-91). A shift in disulfide formation between cysteines at positions 71 and 80 reflected an interruption in the periodicity of hydrophobic residues in the region 71AEKILEETEKE81. To understand how the N-terminal domain of H is formed, we determined for the first time, to our knowledge, the solution NMR structure of H(1-47), which revealed an alpha-helix between residues 15-42 and a flexible N-terminal stretch. The alpha-helix includes a kink that would bring the two helices of the C-terminus into the coiled-coil arrangement. H(1-47) revealed a strip of alanines involved in dimerization, which were tested by exchange to single cysteines in subunit H mutants.
Biuković
Goran
G
School of Biological Sciences, Nanyang Technological University, Singapore.
Gayen
Shovanlal
S
Pervushin
Konstantin
K
Grüber
Gerhard
G
D025181:ATP Synthetase Complexes / Q000737:chemistry* / Q000235:genetics; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D002942:Circular Dichroism; D004058:Diffusion; D004591:Electrophoresis, Polyacrylamide Gel; D017017:Methanococcus / Q000201:enzymology*; D008958:Models, Molecular; D009154:Mutation; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D011522:Protons; D014466:Ultraviolet Rays
D019843:Archaeal Proteins; D009587:Nitrogen Isotopes; D021122:Protein Subunits; D011522:Protons; D025181:ATP Synthetase Complexes