title: Indispensable glutamic acid residue-139 of NtpK proteolipid in the reaction of vacuolar Na(+)-translocating ATPase in Enterococcus hirae.
abstract: Enterococcus hirae vacuolar ATPase catalyzes translocation of Na+ or Li+ coupled with ATP hydrolysis. It is suggested that the glutamic acid residue (Glu139) of NtpK proteolipid subunit of this multisubunit enzyme is the binding site of these ions for translocation. Here we established a complementation system for the ntpK gene with its deletion mutant, and found that the ATPase activity disappeared upon replacement of Glu139 by aspartic acid. The side-chain length of this acidic residue of NtpK is thus important for this ATPase reaction.
authors.affiliation: Department of Biological Science and Technology, Science University of Tokyo, Chiba, Japan. takase@y105hp.tb.noda.sut.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Takase
authors.forename: I
authors.initials: I
authors.lastname: Yamato
authors.forename: K
authors.initials: K
authors.lastname: Igarashi
authors.forename: Y
authors.initials: Y
authors.lastname: Kakinuma
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics; D027682:Cation Transport Proteins; D016983:Enterococcus / Q000201:enzymology* / Q000235:genetics; D018698:Glutamic Acid / Q000737:chemistry*; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D012964:Sodium / Q000378:metabolism; D014178:Translocation, Genetic; D014617:Vacuoles / Q000201:enzymology
chemical_list: D027682:Cation Transport Proteins; D018698:Glutamic Acid; D012964:Sodium; D000251:Adenosine Triphosphatases; C021838:sodium-translocating ATPase