FACTORS INFLUENCING PS-II PARTICLE ARRAY FORMATION IN ARABIDOPSIS-THALIANA CHLOROPLASTS AND THE RELATIONSHIP OF SUCH ARRAYS TO THE THERMOSTABILITY OF PS-II
Nm. Tsvetkova et al., FACTORS INFLUENCING PS-II PARTICLE ARRAY FORMATION IN ARABIDOPSIS-THALIANA CHLOROPLASTS AND THE RELATIONSHIP OF SUCH ARRAYS TO THE THERMOSTABILITY OF PS-II, Biochimica et biophysica acta. Bioenergetics, 1228(2-3), 1995, pp. 201-210
Chloroplasts of the thermal-stable fatty acid desaturase mutants JB67
and LK3 of Arabidopsis thaliana are characterised by the presence of r
egular arrays of freeze-fracture particles associated with the core an
d light-harvesting antennae of Photosystem II (Tsvetkova et al. (1994)
Biochim. Biophys. Acta 1192, 263-271). Similar arrays were found to b
e induced in the membranes of chloroplasts isolated from wild-type pla
nts by resuspending the chloroplasts in media containing Tricine and/o
r high concentrations of compatible co-solutes such as sorbitol. The t
hermal stability of their chloroplasts was also increased under such c
onditions. The increased tendency to form PS II particle arrays, and t
he enhanced thermal stability of PS II, in chloroplasts isolated from
the mutants and wild-type chloroplasts suspended in different media, a
ppear to be reflections of the increased stability of protein-protein
interactions between and within PS II units, respectively. The role of
lipids in determining the formation of freeze-fracture particle array
s in the mutants is discussed in terms of the observed changes in lipi
d composition and their possible role in the control of lipid/protein
synthesis.