標題: Functional Investigation of Transmembrane Helix 3 in H+-Translocating Pyrophosphatase
作者: Lee, Ching-Hung
Chen, Yen-Wei
Huang, Yun-Tzu
Pan, Yih-Jiuan
Lee, Chien-Hsien
Lin, Shih-Ming
Huang, Lin-Kun
Lo, Yueh-Yu
Huang, Yu-Fen
Hsu, Yu-Di
Yen, Shih-Chung
Hwang, Jenn-Kang
Pan, Rong-Long
生物資訊及系統生物研究所
Institude of Bioinformatics and Systems Biology
關鍵字: Proton-translocating pyrophosphatase;Proton transport;Transmembrane helix;Site-directed mutagenesis;Coupling efficiency;GxxxG-like motif
公開日期: 1-十二月-2013
摘要: H+-translocating pyrophosphatase (H+-PPase, EC 3.6.1.1) plays an important role in acidifying vacuoles by transporting protons across membranes at the expense of pyrophosphate (PPi) hydrolysis. Vigna radiata H+-PPase (VrH(+)-PPase) contains 16 transmembrane helices (TMs). The hydrophobicity of TM3 is relatively lower than that of most other TMs, and the amino acids in this TM are highly conserved in plants. Furthermore, TM5 and -6, which are the core TMs involving in H+-PPase functions, are near TM3. It is thus proposed that TM3 is associated with H+-PPase activity. To address this possibility, site-directed mutagenesis was applied in this investigation to determine the role of TM3 in VrH(+)-PPase. Upon alanine/serine substitution, T138 and S142, whose side chains face toward the center TMs, were found to be involved in efficient proton transport. G149/S153 and G160/A164 pairs at the crucial termini of the two GxxxG-like motifs are indispensable in maintaining enzymatic activities and conformational stability. Moreover, stability in the vicinity surrounding G149 is pivotal for efficient expression. S153, M161 and A164 are critical for the K+-mediated stimulation of H+-PPase. Taken together, our results demonstrate that TM3 plays essential roles in PPi hydrolysis, proton transport, expression, and K+ stimulation of H+-PPase.
URI: http://dx.doi.org/10.1007/s00232-013-9599-7
http://hdl.handle.net/11536/22923
ISSN: 0022-2631
DOI: 10.1007/s00232-013-9599-7
期刊: JOURNAL OF MEMBRANE BIOLOGY
Volume: 246
Issue: 12
起始頁: 959
結束頁: 966
顯示於類別:期刊論文


文件中的檔案:

  1. 000326625500010.pdf

若為 zip 檔案,請下載檔案解壓縮後,用瀏覽器開啟資料夾中的 index.html 瀏覽全文。