Plant low-molecular-weight phospholipase A2S (PLA2s) are structurally related to the animal secretory PLA2s and are present as a family of isoforms in rice (Oryza sativa).
Recently, we purified to homogeneity and characterized a low-molecular-weight calcium-dependent phospholipase A2 (PLA2) from developing elm seed endosperm. This represented the first purified and characterized PLA2 from a plant tissue. The full sequences of two distinct but homologous rice (Oryza sativa) cDNAs are given here. These encode mature proteins of 1 19 amino acids (PLA2-I, preceded by a 19 amino acid signal peptide) and 128 amino acids (PLA2-II. preceded by a 25 amino acid signal peptide), and were derived from four expressed sequence tag (EST) clones. Both proteins were homologous to the N-terminal amino acid sequence of the elm PLA2. They contained twelve conserved cysteine residues and sequences that are likely to represent the Ca(2+)-binding loop and active-site motif, which are characteristic of animal secretory PLA2s. A soluble PLA2s activity was purified 145 000-fold from green rice shoots. This had the same biochemical characteristics as the elm and animal secretory PLA2s. The purified rice PLA2 consisted of two proteins, with a molecular weight of 12 440 and 12 920, that had identical N-terminal amino acid sequences. This sequence was different from but homologous to the PLA2-I and PLA2-II sequences. Taken together, the results suggest that at least three different low-molecular-weight PLA2s are expressed in green rice shoots. Southern blot analysis suggested that multiple copies of such genes are likely to occur in the rice and in other plant genomes.
Ståhl
U
U
Department of Plant Biology, Swedish University of Agricultural Sciences, Uppsala.
Lee
M
M
Sjödahl
S
S
Archer
D
D
Cellini
F
F
Ek
B
B
Iannacone
R
R
MacKenzie
D
D
Semeraro
L
L
Tramontano
E
E
Stymme
S
S
D000595:Amino Acid Sequence; D000818:Animals; D015139:Blotting, Southern; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018744:DNA, Plant / Q000032:analysis / Q000235:genetics; D020224:Expressed Sequence Tags; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012275:Oryza / Q000201:enzymology / Q000235:genetics*; D010741:Phospholipases A / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D054467:Phospholipases A2; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014197:Trees / Q000201:enzymology / Q000235:genetics
D018076:DNA, Complementary; D018744:DNA, Plant; D007527:Isoenzymes; D010741:Phospholipases A; D054467:Phospholipases A2