Molecular cloning and characterization of a venom phospholipase A2 from the bumblebee Bombus ignitus.
Phospholipase A(2) (PLA(2)) is one of the main components of bee venom. Here, we identify a venom PLA(2) from the bumblebee, Bombus ignitus. Bumblebee venom PLA(2) (Bi-PLA(2)) cDNA, which was identified by searching B. ignitus venom gland expressed sequence tags, encodes a 180 amino acid protein. Comparison of the genomic sequence with the cDNA sequence revealed the presence of four exons and three introns in the Bi-PLA(2) gene. Bi-PLA(2) is an 18-kDa glycoprotein. It is expressed in the venom gland, cleaved between the residues Arg44 and Ile45, and then stored in the venom sac. Comparative analysis revealed that the mature Bi-PLA(2) (136 amino acids) possesses features consistent with other bee PLA(2)s, including ten conserved cysteine residues, as well as a highly conserved Ca(2+)-binding site and active site. Phylogenetic analysis of bee PLA(2)s separated the bumblebee and honeybee PLA(2) proteins into two groups. The mature Bi-PLA(2) purified from the venom of B. ignitus worker bees hydrolyzed DBPC, a known substrate of PLA(2). Immunofluorescence staining of Bi-PLA(2)-treated insect Sf9 cells revealed that Bi-PLA(2) binds at the cell membrane and induces apoptotic cell death.
Xin
Yu
Y
College of Natural Resources and Life Science, Dong-A University, Busan 604-714, Republic of Korea.
Choo
Young Moo
YM
Hu
Zhigang
Z
Lee
Kwang Sik
KS
Yoon
Hyung Joo
HJ
Cui
Zheng
Z
Sohn
Hung Dae
HD
Jin
Byung Rae
BR
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001514:Bee Venoms / Q000201:enzymology*; D001516:Bees; D003001:Cloning, Molecular; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D054467:Phospholipases A2 / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D010802:Phylogeny; D017422:Sequence Analysis, DNA
D001514:Bee Venoms; D054467:Phospholipases A2