Substrate-induced changes in domain interaction of vacuolar H+-Pyrophosphatase

Shen Hsing Hsu, Yueh Yu Lo, Tseng Huang Liu, Yih Jiuan Pan, Yun Tzu Huang, Yuh Ju Sun, Cheng Chieh Hung, Fan Gang Tseng, Chih Wei Yang*, Rong Long Pan

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

7 Scopus citations

Abstract

Single molecule atomic force microscopy (smAFM) was employed to unfold transmembrane domain interactions of a unique vacuolar H+-pyrophosphatase (EC 3.6.1.1) from Vigna radiata . H+-Pyrophosphatase is a membrane-embedded homodimeric protein containing a single type of polypeptide and links PPi hydrolysis to proton translocation. Each subunit consists of 16 transmembrane domains with both ends facing the lumen side. In this investigation, H+-pyrophosphatase was reconstituted into the lipid bilayer in the same orientation for efficient fishing out of the membrane by smAFM. The reconstituted H+-pyrophosphatase in the lipid bilayer showed an authentically dimeric structure, and the size of each monomer was ∼4 nm in length, ∼2 nm in width, and ∼1 nm in protrusion height. Upon extracting the H+-pyrophosphatase out of the membrane, force-distance curves containing 10 peaks were obtained and assigned to distinct domains. In the presence of pyrophosphate, phosphate, and imidodiphosphate, the numbers of interaction curves were altered to 7, 8, and 10, respectively, concomitantly with significant modification in force strength. The substrate-binding residues were further replaced to verify these domain changes upon substrate binding. A working model is accordingly proposed to show the interactions between transmembrane domains of H+-pyrophosphatase in the presence and absence of substrate and its analog.

Original languageEnglish
Pages (from-to)1197-1209
Number of pages13
JournalJournal of Biological Chemistry
Volume290
Issue number2
DOIs
StatePublished - 09 01 2015

Bibliographical note

Publisher Copyright:
© 2015 by The American Society for Biochemistry and Molecular Biology Inc.

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