Biochem. J. (2005) 388
(763–771) (Printed in Great Britain)
Identification, characterization and structure of a new Delta class glutathione transferase isoenzyme
Rungrutai UDOMSINPRASERT*1, Saengtong PONGJAROENKIT†1, Jantana WONGSANTICHON*, Aaron J. OAKLEY‡, La-aied PRAPANTHADARA§, Matthew C. J. WILCE‡ and Albert J. KETTERMAN*2
*Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, 25/25 Putthamonthol Road 4, Salaya, Nakon Pathom 73170, Thailand, †Department of Biology, Faculty of Science, Maejo University, Chiangmai 50290, Thailand, ‡Department of Pharmacology/Crystallography Centre, University of Western Australia, Crawley 6009, Australia, and §Research Institute for Health Sciences, Chiangmai University, Chiangmai 50200, Thailand
The insect GST (glutathione transferase) supergene family encodes a varied group of proteins belonging to at least six individual classes. Interest in insect GSTs has focused on their role in conferring insecticide resistance. Previously from the mosquito malaria vector Anopheles dirus, two genes encoding five Delta class GSTs have been characterized for structural as well as enzyme activities. We have obtained a new Delta class GST gene and isoenzyme from A. dirus, which we name adGSTD5-5. The adGSTD5-5 isoenzyme was identified and was only detectably expressed in A. dirus adult females. A putative promoter analysis suggests that this GST has an involvement in oogenesis. The enzyme displayed little activity for classical GST substrates, although it possessed the greatest activity for DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane] observed for Delta GSTs. However, GST activity was inhibited or enhanced in the presence of various fatty acids, suggesting that the enzyme may be modulated by fatty acids. We obtained a crystal structure for adGSTD5-5 and compared it with other Delta GSTs, which showed that adGSTD5-5 possesses an elongated and more polar active-site topology.
Key words: Anopheles dirus, crystal structure, Delta class glutathione transferase, enzyme characterization, glutathione transferase gene, regulatory element.
Abbreviations used: AP-1, activator protein 1; CDNB, 1-chloro-2,4-dinitrobenzene; DDT, 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane; GST, glutathione transferase; RMSD, root mean square deviation.
1These authors contributed equally to this work.
2To whom correspondence should be addressed (email frakt@mahidol.ac.th).
Received 6 December 2004/14 February 2005; accepted 17 February 2005
Published as BJ Immediate Publication 17 February 2005, DOI 10.1042/BJ20042015
The Biochemical Society, London ©2005
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