Bioinformatic and enzymatic characterization of the MAPEG superfamily

Abstract

The membrane associated proteins in eicosanoid and glutathione metabolism (MAPEG) superfamily includes structurally related membrane proteins with diverse functions of widespread origin. A total of 136 proteins belonging to the MAPEG superfamily were found in database and genome screenings. The members were found in prokaryotes and eukaryotes, but not in any archaeal organism. Multiple sequence alignments and calculations of evolutionary trees revealed a clear subdivision of the eukaryotic MAPEG members, corresponding to the six families of microsomal glutathione transferases (MGST) 1, 2 and 3, leukotriene C 4 synthase (LTC 4 ), 5-lipoxygenase activating protein (FLAP), and prostaglandin E synthase. Prokaryotes contain at least two distinct potential ancestral subfamilies, of which one is unique, whereas the other most closely resembles enzymes that belong to the MGST2 ⁄ FLAP ⁄ LTC 4 synthase families. The insect members are most similar to MGST1 ⁄ prostaglandin E synthase. With the new data available, we observe that fish enzymes are present in all six families, showing an early origin for MAPEG family differentiation. Thus, the evolutionary origins and relationships of the MAPEG superfamily can be defined, including distinct sequence patterns characteristic for each of the subfamilies. We have further investigated and functionally characterized representative gene products from Escherichia coli, Synechocystis sp., Arabidopsis thaliana and Drosophila melanogaster, and the fish liver enzyme, purified from pike (Esox lucius). Protein overexpression and enzyme activity analysis demonstrated that all proteins catalyzed the conjugation of 1-chloro-2,4-dinitrobenzene with reduced glutathione. The E. coli protein displayed glutathione transferase activity of 0.11 lmolAEmin )1 AEmg)1 in the membrane fraction from bacteria overexpressing the protein. Partial purification of the Synechocystis sp. protein yielded an enzyme of the expected molecular mass and an N-terminal amino acid sequence that was at least 50% pure, with a specific activity towards 1-chloro-2,4-dinitrobenzene of 11 lmolAEmin )1 AEmg )1 . Yeast microsomes expressing the Arabidopsis enzyme Abbreviations BSA, bovine serum albumin;

Transcriptomics of induced defense responses to greenbug aphid feeding in near isogenic wheat lines

“…The only GST transcript upregulated in RB (ta.1878.3.s1_at) was putatively associated with membrane associated proteins in eicosanoid and glutathione metabolism (MAPEG-like protein) and is also involved in detoxification functions [69].…”

Glutathione Transferases

“…Of these genes, at least 52 are transcribed, and 41 of the respective proteins have been shown to possess GSH-dependent catalytic activities (Bresell et al, 2005;. Most classes are small and possess 1 to 4 members.…”

“…(Gruhler et al, 2005), 7 (Sappl et al, 2004), 8 (Heazlewood et al, 2004), 9 (Carter et al, 2004), a Miscellaneous entry in PPDB ). ‡ Nature of in vitro activity, with GST = glutathione transferase, TT = thiol transferase, GPOX = GSH-dependent lipid peroxidase, MAAI = maleylacetoacetate isomerase ), except b (Dixon et al, 2002b), c (Dixon and Edwards, 2006) and d (Bresell et al, 2005). Other references: e (Kitamura et al, 2004), f (Chen et al, 2007) Figure 4.…”

Structural basis for induced formation of the inflammatory mediator prostaglandin E 2

“…The protein is a member of the MAPEG protein family, which includes 5-lipoxygenase activating protein (FLAP), leukotriene C 4 synthase (LTC4S), microsomal glutathione transferase (MGST)1, MGST2, and MGST3 (2,3). MPGES1 is the most efficient PGES known and catalyzes the oxidoreduction of prostaglandin endoperoxide H 2 into PGE 2 with an apparent k cat /K m of 310 mM Ϫ1 s Ϫ1 [supporting information (SI) Fig.…”