© 2006 The Japanese Biochemical Society.
Regular Paper |
Deletion Analysis of the Subunit Genes of V-Type Na+-ATPase from Enterococcus hirae
1 Genomic Sciences Center, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045; 2 Lab. of Seeds Finding Technology, Eisai Co., Ltd., 1-3, Tokodai 5-choume, Tsukuba, Ibaraki 300-2635; and 3 Faculty of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama 790-8566; and 4 Department of Biological Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510
* To whom correspondence should be addressed. Phone: +81-4-7124-1501 (Ext. 4405), Fax: +81-4-7125-1841, E-mail, iyamato{at}rs.noda.tus.ac.jp
The V1Vo-ATPase from Enterococcus hirae catalyzes ATP hydrolysis coupled with sodium translocation. Mutants with deletions of each of 10 subunits (NtpA, B, C, D, E, F, G, H, I, and K) were constructed by insertion of a chloramphenicol acetyltransferase gene into the corresponding subunit gene in the genome. Measurements of cell growth rates, 22Na+ efflux activities, and ATP hydrolysis activities of the membranes of the deletion mutants indicated that V-ATPase requires nine of the subunits, the exception being the NtpH subunit. The results of Western blotting and V1-ATPase dissociation analysis suggested that the A, B, C, D, E, F, and G subunits constitute the V1 moiety, whereas the V0 moiety comprises the I and K subunits.