ISSN:
1573-4943
Keywords:
Tonoplast
;
vacuolar H+-ATPase
;
hydrostatic pressure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract A high-hydrostatic-pressure technique was employed to study the structure-function relationship of plant vacuolar H+-ATPase from etiolated mung bean seedlings (Vigna radiata L.). When isolated vacuolar H+-ATPase was subjected to hydrostatic pressure, the activity of ATP hydrolysis was markedly inhibited in a time-, protein concentration- and pressure-dependent manner. The pressure treatment decreased both V max and K m of solubilized vacuolar H+-ATPase, implying an increase in ATP binding affinity, but a decrease in the ATP hydrolysis activity. Physiological substrate, Mg2+-ATP, augmented the loss of enzymatic activity upon pressure treatment. However, ADP, AMP, and Pi exerted substantial protective effects against pressurization. Steady-state ATP hydrolysis was more sensitive to pressurization than single-site ATPase activity. The inactivation of solubilized vacuolar H+-ATPase by pressure may result from changes in protein–protein interaction. The conformational change of solubilized vacuolar H+-ATPase induced by hydrostatic pressure was further determined by spectroscopic techniques. The inhibition of vacuolar H+-ATPase under pressurization involved at least two steps. Taken together, our work indicates that subunit–subunit interaction is crucial for the integrity and the function of plant vacuolar H+-ATPase. It is also suggested that the assembly of the vacuolar H+-ATPase complex is probably not random, but follows a sequestered pathway.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1022535701279
Permalink