Changes in phospholipid composition and phospholipase D activity during the differentiation of Physarum polycephalum.
Changes in phospholipid composition and phospholipase D activity were observed during a differentiation from haploid myxoamoebae to diploid plasmodia of a true slime mold, Physarum polycephalum. In the amoeboid stage, the main components of phospholipid fraction were phosphatidylethanolamine (PE, 43.3%), phosphatidylcholine (PC, 28.8%) and phosphatidylinositol (PI, 8.0%), but in the plasmodial stage, PC was dominant (40.7%) and other main components were PE (31.5%) and phosphatidic acid (PA, 11.0%). The specific activity of phospholipase D in the plasmodia was 5.7-times higher than that in the myxoamoebae when measured in the presence of Ca2+ at the alkaline pH. In the amoeboid stage, phospholipase A activity (A1 or A2) was detected at the alkaline pH with Ca2+. Phospholipase D activity in the plasmodia was characterized: pH optimum was 6.0; Ca2+ was required for the reaction and Ba2+ could substitute partly for Ca2+; PE was the best substrate for the hydrolytic activity and PC and PI were not appreciably hydrolyzed; and all detergents tested inhibited the enzyme activity.
Minowa
A
A
Department of Biology, Faculty of Science, Ochanomizu University, Tokyo, Japan.
Kobayashi
T
T
Shimada
Y
Y
Maeda
H
H
Murakami-Murofushi
K
K
Ohta
J
J
Inoue
K
K
D002118:Calcium / Q000494:pharmacology; D006868:Hydrolysis; D009024:Morphogenesis; D010739:Phospholipase D / Q000378:metabolism*; D010740:Phospholipases / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D010804:Physarum / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D013379:Substrate Specificity
D010743:Phospholipids; D010740:Phospholipases; D010739:Phospholipase D; D002118:Calcium