Premium
V‐ATPase is a novel evolutionarily conserved cytohesin‐signaling receptor
Author(s) -
Hosokawa Hiroyuki,
Dip Phat V.,
Merkulova Maria,
Bakulina Anastasia,
Zhuang Zhenjie,
Khatri Ashok,
Jian Xiaoying,
Randazzo Paul A.,
Ausiello Dennis A.,
Grüber Gerhard,
Marshansky Vladimir
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1031.23
Subject(s) - gtp' , microbiology and biotechnology , amino acid , endosome , peptide sequence , atpase , protein subunit , guanine nucleotide exchange factor , chemistry , biology , biochemistry , receptor , signal transduction , gene , enzyme
Previously, we reported an acidification‐dependent interaction of the endosomal V‐ATPase with cytohesin‐2, a GDP/GTP‐exchange factor (GEF), suggesting that it functions as a pH‐sensing receptor. Here, we have studied the molecular mechanism of signaling between the V‐ATPase, cytohesin‐2 and Arf GTP‐binding proteins. We found that part of the N‐terminal cytosolic tail of the V‐ATPase a2‐subunit (a2N 1–402 ), corresponding to its first seventeen amino acids (a2N 1–17 ), potently modulates the GDP/GTP‐exchange activity of cytohesin‐2. Moreover, this peptide strongly inhibits GEF‐activity via direct interaction with the Sec7 domain of cytohesin‐2. The structure of a2N 1–17 and its amino acids F 5 , M 10 and Q 14 involved in interaction with Sec7 domain were determined by NMR spectroscopy analysis. In silico docking experiments revealed that part of the V‐ATPase formed by its a2N 1–17 epitope competes with the Switch 2 region of Arf1 and Arf6 for a binding on the Sec7 domain of cytohesin‐2. Moreover, the amino acid sequence alignment and GEF‐activity experiments also uncovered the conserved character of signaling between all four (a1‐a4) a‐subunit isoforms of mammalian V‐ATPase and cytohesin‐2. Thus, here we have uncovered an evolutionarily conserved function of the V‐ATPase as a novel cytohesin‐signaling receptor. Supported by grants NIH DK038452, BADERC DK057521–08 to VM and by A*STAR BMRC09/1/22/19/609 to GG.