MF2110019 4-aminobutyrate aminotransferase 1ohv X-ray 2.30 Homodimer Sus scrofa 14534310 Storici P, De Biase D, Bossa F, Bruno S, Mozzarelli A, Peneff C, Silverman RB, Schirmer T J. Biol. Chem. 2004 1 279 363-73 Gamma-aminobutyric acid aminotransferase (GABA-AT) is a pyridoxal 5'-phosphate-dependent enzyme responsible for the degradation of the inhibitory neurotransmitter GABA. GABA-AT is a validated target for antiepilepsy drugs because its selective inhibition raises GABA concentrations in brain. The antiepilepsy drug, gamma-vinyl-GABA (vigabatrin) has been investigated in the past by various biochemical methods and resulted in several proposals for its mechanisms of inactivation. In this study we solved and compared the crystal structures of pig liver GABA-AT in its native form (to 2.3-A resolution) and in complex with vigabatrin as well as with the close analogue gamma-ethynyl-GABA (to 2.3 and 2.8 A, respectively). Both inactivators form a covalent ternary adduct with the active site Lys-329 and the pyridoxal 5'-phosphate (PLP) cofactor. The crystal structures provide direct support for specific inactivation mechanisms proposed earlier on the basis of radio-labeling experiments. The reactivity of GABA-AT crystals with the two GABA analogues was also investigated by polarized absorption microspectrophotometry. The spectral data are discussed in relation to the proposed mechanism. Intriguingly, all three structures revealed a [2Fe-2S] cluster of yet unknown function at the center of the dimeric molecule in the vicinity of the PLP cofactors. GO:0047298 (S)-3-amino-2-methylpropionate transaminase activity GO:0051537 2 iron, 2 sulfur cluster binding GO:0003867 4-aminobutyrate transaminase activity GO:0034386 4-aminobutyrate GO:0042802 identical protein binding GO:0046872 metal ion binding GO:0042803 protein homodimerization activity GO:0030170 pyridoxal phosphate binding GO:0032145 succinate-semialdehyde dehydrogenase binding GO:0032144 4-aminobutyrate transaminase complex GO:0005829 cytosol GO:0005759 mitochondrial matrix GO:0005739 mitochondrion GO:0048148 behavioral response to cocaine GO:0009450 gamma-aminobutyric acid catabolic process 2 1 Homooligomeric enzymes Homodimeric enzymes All chains according to the most probable oligomerization state stored in PDBe were considered. A 4-aminobutyrate aminotransferase, mitochondrial Sus scrofa P80147 39 499 92% MASVLLTRRLACSFRHNHRLLVPGWRHISQAAAKVDVEFDYDGPLMKTEVPGPRSRELMKQLNIIQNAEAVHFFCNYEESRGNYLVDVDGNRMLDLYSQISSIPIGYSHPALVKLVQQPQNVSTFINRPALGILPPENFVEKLRESLLSVAPKGMSQLITMACGSCSNENAFKTIFMWYRSKERGQSAFSKEELETCMINQAPGCPDYSILSFMGAFHGRTMGCLATTHSKAIHKIDIPSFDWPIAPFPRLKYPLEEFVKENQQEEARCLEEVEDLIVKYRKKKKTVAGIIVEPIQSEGGDNHASDDFFRKLRDISRKHGCAFLVDEVQTGGGSTGKFWAHEHWGLDDPADVMTFSKKMMTGGFFHKEEFRPNAPYRIFNTWLGDPSKNLLLAEVINIIKREDLLSNAAHAGKVLLTGLLDLQARYPQFISRVRGRGTFCSFDTPDESIRNKLISIARNKGVMLGGCGDKSIRFRPTLVFRDHHAHLFLNIFSDILADFK 500 secondary structure helix 24 38 secondary structure helix 48 52 secondary structure helix 69 74 secondary structure helix 81 90 secondary structure helix 93 99 secondary structure helix 110 118 secondary structure helix 119 123 secondary structure helix 135 157 secondary structure helix 162 171 secondary structure helix 193 200 secondary structure helix 203 208 secondary structure helix 226 229 secondary structure helix 230 255 secondary structure helix 277 291 secondary structure helix 311 317 secondary structure helix 328 332 secondary structure helix 340 343 secondary structure helix 357 374 secondary structure helix 375 398 secondary structure helix 418 432 secondary structure helix 453 470 secondary structure strand 56 58 secondary structure strand 64 67 secondary structure strand 129 133 secondary structure strand 181 185 secondary structure strand 217 218 secondary structure strand 259 264 secondary structure strand 294 298 secondary structure strand 324 327 secondary structure strand 334 338 secondary structure strand 403 408 secondary structure strand 411 415 secondary structure strand 434 435 secondary structure strand 437 439 secondary structure strand 443 446 pfam PF00202 Aminotransferase class-III 67 496 B 4-aminobutyrate aminotransferase, mitochondrial Sus scrofa P80147 39 499 92% MASVLLTRRLACSFRHNHRLLVPGWRHISQAAAKVDVEFDYDGPLMKTEVPGPRSRELMKQLNIIQNAEAVHFFCNYEESRGNYLVDVDGNRMLDLYSQISSIPIGYSHPALVKLVQQPQNVSTFINRPALGILPPENFVEKLRESLLSVAPKGMSQLITMACGSCSNENAFKTIFMWYRSKERGQSAFSKEELETCMINQAPGCPDYSILSFMGAFHGRTMGCLATTHSKAIHKIDIPSFDWPIAPFPRLKYPLEEFVKENQQEEARCLEEVEDLIVKYRKKKKTVAGIIVEPIQSEGGDNHASDDFFRKLRDISRKHGCAFLVDEVQTGGGSTGKFWAHEHWGLDDPADVMTFSKKMMTGGFFHKEEFRPNAPYRIFNTWLGDPSKNLLLAEVINIIKREDLLSNAAHAGKVLLTGLLDLQARYPQFISRVRGRGTFCSFDTPDESIRNKLISIARNKGVMLGGCGDKSIRFRPTLVFRDHHAHLFLNIFSDILADFK 500 secondary structure helix 24 38 secondary structure helix 69 74 secondary structure helix 81 90 secondary structure helix 93 99 secondary structure helix 110 118 secondary structure helix 119 123 secondary structure helix 135 157 secondary structure helix 162 171 secondary structure helix 193 200 secondary structure helix 203 208 secondary structure helix 226 229 secondary structure helix 230 255 secondary structure helix 277 291 secondary structure helix 311 317 secondary structure helix 328 332 secondary structure helix 340 343 secondary structure helix 357 374 secondary structure helix 375 398 secondary structure helix 418 432 secondary structure helix 453 470 secondary structure strand 56 58 secondary structure strand 64 67 secondary structure strand 129 133 secondary structure strand 181 185 secondary structure strand 217 218 secondary structure strand 259 264 secondary structure strand 294 298 secondary structure strand 324 327 secondary structure strand 334 338 secondary structure strand 403 408 secondary structure strand 411 415 secondary structure strand 434 435 secondary structure strand 437 439 secondary structure strand 443 445 pfam PF00202 Aminotransferase class-III 67 496 Direct evidence The full structure participates in mutual synergistic folding. Aminotransferase class-III The equilibrium unfolding of pig liver 4-aminobutyrate aminotransferase by urea was found to be a cooperative process. The kinetic results indicated that the aminotransferase unfolds in a single kinetic phase (PMID:8075151). A N/A B N/A MF2110019 MF7000973