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Copyright of Chinese Journal of Preventive Veterinary Medicine / Zhongguo Yufang Shouyi Xuebao is the property of Chinese Journal of Preventive Veterinary Medicine Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Subunit G is an essential stalk subunit of the eukaryotic proton pump V1VO ATPase. Previously the structure of the N-terminal region, G1 – 59, of the 13kDa subunit G was solved at higher resolution. Here solution NMR was performed to determine the structure of the recombinant C-terminal region (G61 – 101) of subunit G of the Saccharomyces cerevisiae V1VO ATPase. The protein forms an extended α-helix between residues 64 and 100, whereby the first five- and the last residues of G61 – 101 are flexible. The surface charge distribution of G61 – 101 reveals an amphiphilic character at the C-terminus due to positive and negative charge distribution at one side and a hydrophobic surface on the opposite side of the structure. The hydrophobic surface pattern is mainly formed by alanine residues. The alanine residues 72, 74 and 81 were exchanged by a single cysteine in the entire subunit G. Cysteines at positions 72 and 81 showed disulfide formation. In contrast, no crosslink could be formed for the mutant Ala74Cys. Together with the recently determined NMR solution structure of G1 – 59, the presented solution structure of G61 – 101 enabled us to present a first structural model of the entire subunit G of the S. cerevisiae V1VO ATPase. [ABSTRACT FROM AUTHOR]

Abstract: Understanding the structural traits of subunit G is essential, as it is needed for V1VO assembly and function. Here solution NMR of the recombinant N- (G1–59) and C-terminal segment (G61–114) of subunit G, has been performed in the absence and presence of subunit d of the yeast V-ATPase. The data show that G does bind to subunit d via its N-terminal part, G1–59 only. The residues of G1–59 involved in d binding are Gly7 to Lys34. The structure of G1–59 has been solved, revealing an α-helix between residues 10 and 56, whereby the first nine- and the last three residues of G1–59 are flexible. The surface charge distribution of G1–59 reveals an amphiphilic character at the N-terminus due to positive and negative charge distribution at one side and a hydrophobic surface on the opposite side of the structure. The C-terminus exhibits a strip of negative residues. The data imply that G1–59–d assembly is accomplished by hydrophobic interactions and salt-bridges of the polar residues. Based on the recently determined NMR structure of segment E18–38 of subunit E of yeast V-ATPase and the presently solved structure of G1–59, both proteins have been docked and binding epitopes have been analyzed. [Copyright &y& Elsevier]