The tumor suppressor gene H-Rev107 functions as a novel Ca2+-independent cytosolic phospholipase A1/2 of the thiol hydrolase type.
H-Rev107 is a protein that was previously cloned as a negative regulator of proto-oncogene Ras and classified as a class II tumor suppressor. Its structural similarity to lecithin retinol acyltransferase and Ca2+-independent phosphatidylethanolamine (PE) N-acyltransferase led us to analyze H-Rev107 as an enzyme involved in phospholipid metabolism. Here, we show that recombinant H-Rev107s from rat, human, and mouse possess phospholipase (PL) A1 or A2 activity toward phosphatidylcholine (PC). Further examination with purified recombinant protein revealed that H-Rev107 functions as a cytosolic Ca2+-independent PLA(1/2) for PC and PE with higher PLA1 activity than PLA2 activity. Dithiothreitol and iodoacetic acid exhibited stimulatory and inhibitory effects, respectively. Histidine-21 and cysteine-111 of rat H-Rev107 were presumed to form a catalytic dyad based on database analysis, and their single mutants were totally inactive. These results suggested that H-Rev107 is a hydrolase of the thiol type. The N-terminal proline-rich and C-terminal hydrophobic domains of H-Rev107 were earlier reported to be responsible for the regulation of cell proliferation. Analysis of deletion mutants indicated that these domains are also catalytically essential, suggesting relevance of the catalytic activity to the anti-proliferative activity.
Uyama
Toru
T
Department of Biochemistry, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan.
Morishita
Jun
J
Jin
Xing-Hua
XH
Okamoto
Yasuo
Y
Tsuboi
Kazuhito
K
Ueda
Natsuo
N
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D016147:Genes, Tumor Suppressor; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D054466:Phospholipases A1 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D054512:Phospholipases A2, Calcium-Independent; D054510:Phospholipases A2, Cytosolic / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D017931:DNA Primers; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; C000715470:MAS1 protein, human; D011506:Proteins; D000090063:Proto-Oncogene Mas; D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins; D054466:Phospholipases A1; C490065:PLAAT3 protein, human; D054512:Phospholipases A2, Calcium-Independent; D054510:Phospholipases A2, Cytosolic; C490066:Plaat3 protein, mouse; C085466:Plaat3 protein, rat; D002118:Calcium