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A newly discovered tenth atp gene and the conserved atpI gene of a Bacillus atp operon have a role in Mg2+ uptake

Domenii publicaţii > Biologie + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: Hicks, D.B., Wang, Z., Wei, Y., Kent, R., Guffanti, A.A., Banciu, H., Bechhofer, D.H. and Krulwich, T.A

Editorial: Proc. Natl Acad Sci USA , 100 (18), p.10213-1021, 2003.


The atp operon of alkaliphilic Bacillus pseudofirmus OF4, as in most
prokaryotes, contains the eight structural genes for the F-ATPase
(ATP synthase), which are preceded by an atpI gene that encodes
a membrane protein of unknown function. A tenth gene, atpZ, has
been found in this operon, which is upstream of and overlapping
with atpI. Most Bacillus species, and some other bacteria, possess
atpZ homologues. AtpZ is predicted to be a membrane protein with
a hairpin topology, and was detected by Western analyses. Deletion
of atpZ, atpI, or atpZI from B. pseudofirmus OF4 led to a
requirement for a greatly increased concentration of Mg2 for
growth at pH 7.5. Either atpZ, atpI, or atpZI complemented the
similar phenotype of a triple mutant of Salmonella typhimurium
(MM281), which is deficient in Mg2 uptake. atpZ and atpI, separately
and together, increased theMg2-sensitive 45Ca2 uptake by
vesicles of an Escherichia coli mutant that is defective in Ca2 and
Na efflux. We hypothesize that AtpZ and AtpI, as homooligomers,
and perhaps as heterooligomers, are Mg2 transporter, Ca2 transporter,
or channel proteins. Such proteins could provide Mg2,
which is required by ATP synthase, and also support charge
compensation, when the enzyme is functioning in the hydrolytic
direction; e.g., during cytoplasmic pH regulation.

Cuvinte cheie: atp operon, F-type ATP synthase, alkaliphilic, magnesium, ORF