R. Gabbayazaria et al., THE INVOLVEMENT OF A VANADATE-SENSITIVE ATPASE IN PLASMA-MEMBRANES OFA SALT-TOLERANT CYANOBACTERIUM, Physiologia Plantarum, 90(4), 1994, pp. 692-698
Plasma membranes of the marine cyanobacterium Spirulina subsalsa were
tested for ATPase activity, and for involvement in salt stress. Transi
tion of cells from saline to hypersaline medium enhances the respirato
ry activity associated with extrusion of Na+ and Cl-, and persisting s
alt stress induces synthesis of respiratory enzymes in the plasma memb
ranes. The membranes possess an ATPase, specific for ATP and Mg2+ and
sensitive to orthovanadate and dicyclohexylcarbodiimide. Immunoblot an
alysis of plasma membrane polypeptides from Spirulina subsalsa with an
ti-Arabidopsis H+-ATPase serum identified a single polypeptide of 100
kDa, which cross-reacted with the antibodies. An unusual feature of th
is ATPase is a specific stimulation by Na+ ions. Prolonged adaptation
of S. subsalsa cells to hypersaline conditions induced an increase in
ATPase activity in subsequent plasma membrane preparations, as well as
a higher content of the 100 kDa polypeptide. It is suggested that the
ATPase investigated is an H+-pump, which is involved in extrusion of
Na+ and in conferring resistance to salt stress.