Molecular cloning and heterologous expression of a glutathione S-transferase involved in insecticide resistance from the diamondback moth, Plutella xylostella.
Four glutathione S-transferase (GST, EC 2.5.1.18) isozymes have been characterized in the larvae of the diamondback moth (DBM), Plutella xylostella L., a cosmopolitan insect pest of crucifiers. This work aimed at cloning and heterologously expressing the cDNA of DBM GST-3, an isozyme involved in this insect resistance to some organophosphorus insecticides, and studying the molecular basis for its increased expression in the resistant strains. Reverse-transcription polymerase chain reaction (RT-PCR) using midgut mRNA from a methyl parathion resistant MPA strain and degenerate primers complimentary to the N-terminal and internal amino acid sequences of GST-3 generated a 128 bp DNA product. A clone of 809 bp, obtained by screening a midgut cDNA library of MPA strain using this PCR product as probe, encoded a protein of 216 amino acids (calculated Mr 24,083 and pI 8.50). This GST of DBM, PxGST3, shared the highest (46.3%) amino acid sequence identity, among insects, to MsGST1 of Manduca sexta. PxGST3 mRNA level was considerably higher in MPA than in susceptible strains, and Southern blots suggested that gene amplification was probably not involved in the increased expression of this GST isozyme. Enzymatically active PxGST3 expressed heterologously in E. coli exhibited similar biochemical and toxicological properties as GST-3 purified from DBM larvae. It is the first cloned GST with a well-defined role in insecticide resistance.
Department of Entomology, National Chung-Hsing University, Taichung, Taiwan, ROC.
H S
HS
Huang
N T
NT
Hu
Y E
YE
Yao
C Y
CY
Wu
S W
SW
Chiang
C N
CN
Sun
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005982:Glutathione Transferase / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D007313:Insecta / Q000235:genetics; D007305:Insecticide Resistance; D007306:Insecticides; D008969:Molecular Sequence Data; D009036:Moths / Q000201:enzymology* / Q000235:genetics; D009943:Organophosphorus Compounds; D010802:Phylogeny; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D007306:Insecticides; D009943:Organophosphorus Compounds; D012333:RNA, Messenger; D011994:Recombinant Proteins; D005982:Glutathione Transferase