Inhibition by Cu2+ and Cd2+ of a mu-class glutathione S-transferase from shrimp Litopenaeus vannamei.
Glutathione S-transferases (GSTs) are a family of detoxifying enzymes that catalyze the conjugation of glutathione (GSH) to electrophiles, thereby increasing the solubility of xenobiotics and aiding its excretion from the cell. The present work presents the inhibition of a mu-class GST of the marine shrimp Litopenaeus vannamei by copper (Cu2+) and cadmium (Cd2+). The protein was overexpressed in bacteria and its enzymatic activity measured using 1-chloro-2,4-dinitrobenzene. The mean inhibitory concentration (IC(50)) for shrimp GST against Cu2+) was 4.77 microM and for Cd2+ was 0.39 microM. A molecular model of the protein based on the crystal structure of a maize GST bound to cadmium showed that the metal binds in the GSH-binding site by coordination with Asp and Gln residues. These results are consistent with the experimental data and suggest that sublethal concentration of metals may affect the capacity of the organism to detoxify pesticides or xenobiotics.
Centro de Investigación en Alimentación y Desarrollo, A. C (CIAD). Carretera a Ejido La Victoria km 0.6, PO Box 1735, Hermosillo, Sonora 83000, México.
Alex J
AJ
Salazar-Medina
Leticia
L
García-Rico
Karina D
KD
García-Orozco
Elisa
E
Valenzuela-Soto
Carmen A
CA
Contreras-Vergara
Rodrigo
R
Arreola
Aldo
A
Arvizu-Flores
Rogerio R
RR
Sotelo-Mundo
D000818:Animals; D001665:Binding Sites; D002104:Cadmium / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics; D033561:Penaeidae / Q000201:enzymology* / Q000235:genetics; D010575:Pesticides / Q000737:chemistry; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics; D015262:Xenobiotics / Q000737:chemistry; D003313:Zea mays / Q000201:enzymology / Q000235:genetics
D010575:Pesticides; D010940:Plant Proteins; D011994:Recombinant Proteins; D015262:Xenobiotics; D002104:Cadmium; D003300:Copper; D005982:Glutathione Transferase