The following text describes a protein:
Function:
Highly reducing polyketide synthase; part of the gene cluster that mediates the biosynthesis of ochratoxin A (OTA), a mycotoxin composed of a chlorinated type I polyketide dihydroisocoumarin moiety linked to L-phenylalanine, and demonstrated to have nephrotoxic, immunotoxic, genotoxic, neurotoxic, and teratogenic properties. OtaA catalyzes the condensation of one acetate and 4 malonate units to form the isocoumarin group. The pathway begins with the highly reducing polyketide synthase otaA that catalyzes the formation of the isocoumarin group during the initial stages of biosynthesis, starting from one acetate and 4 malonate units, to originate the characteristic pentaketide skeleton 7-methylmellein (7-MM) of the OTA molecule. The newly identified cyclase otaY might be involved in the polyketide cyclization reaction during the initial steps of the OTA biosynthesis. 7-MM is then oxidized into 7-carboxymellein (also called ochratoxin beta) by the cytochrome P450 monooxygenase otaC. The NRPS encoded by the otaB gene is involved in the linking of phenylalanine to the dihydroisocoumarin ring. The reaction catalyzed by NRPS results in the production of ochratoxin B (OTB), which is the non-chlorinated analog of OTA and which subsequently serves as the substrate of the halogenase otaD for chlorination activity to form the final molecular structure of OTA, containing a chlorine atom in the C-5 position of the molecule (Probable).
Domain:
Multidomain protein; including a ketosynthase (KS) that catalyzes repeated decarboxylative condensation to elongate the polyketide backbone; a malonyl-CoA:ACP transacylase (MAT) that selects and transfers the extender unit malonyl-CoA; a dehydratase (DH) domain that reduces hydroxyl groups to enoyl groups; a methyltransferase (CMeT) domain responsible for the incorporation of methyl groups; an enoylreductase (ER) domain that reduces enoyl groups to alkyl group; a ketoreductase (KR) domain that catalyzes beta-ketoreduction steps; and an acyl-carrier protein (ACP) that serves as the tether of the growing and completed polyketide via its phosphopantetheinyl arm.
Sequence:
MSSAPIPQSEPLAIIGLACKYANGIDSPEALYEQVMAARCMHGAMPSNRMDASFYYHPTSEATGTSYSKGGYFLNCDLNAFDSPFFQLSEIDVMAMDPQQKMLLENVYHALENAGIPLKNAISSPTSVFVGCSNNDHLALANSDLLLSLKGKGTGTSPSILANRVSWFYDFQGTSQTIDTACSSSLVAFHQGCMDVRAGKSAMSIISGINLIEHPGPTLYLSSLGVLSPDGKSMSFDARANGYGRGEGVGTVIVKPLQAALRDGNRIRAIVRSTGSNQDGRTPGITVPNPSAQERLIHDVYRVADLDPRRTGYVEAHGTGTQVGDPLEVQAILAALGVARDSPLYVGSVKSVLGHLEGGAGLAGLISATLAVESKMIPPVAGLQSLNPKIPQRDDLKFAREATPWPRWDVRRASINSFGFGGTNAHAVVEDVEGFFADLFGQYIPGALPAPEVDTSLETTPMLSKPLMSGNASNQSVQSWSTSRLFVISAFDEAGIQRNTSALAEYLDSKSTTADTDGEDRLLNNLCHTLNEKRTRFDWRSYHVADSIASLRESLQHSRAIRQSSAPKPIRFVFTGQGANWAGMACDMLKYPLFRRRIQEAAAYLRELGSGWDLFERMTSKAGELDEPTFAQSSCVAVQVALVDLLASWKVVPETVVGHSSGEIAAAYCAGHISRQAAWKVAFCRGKVCARRTDGQGRMLAAAMPVHQLERVVARVNKGQPTSVKIGCYNSPRNLTLTGRYDDILRLKLELDDVGALNRMLPVKVAYHSDYMQDAAPEYLSLLGEILDGGDTIHKDASIQMISSVTGQPVPAGDVQQASYWVKNLVSPVRFCTALLASMEFPGTTGKREDTLIEIGPHSTLRSAIKESFAEVPEYQSVQYGSLLKRYETNGSTILHTLGMMFCSGHEISLAAINDRRVGTRKIPMLLTGLPGYAFDHSRSVRGTSRRIEQVKFPTYNRHELLGVPVEDSNPYEQRWRNVLRPDDLPWLRMNRMKGQIHFPGVAYILMATEALQQRVARTMTIPRVRIANMSILAPLQVPDSPSGVEIQVSIYPTNVRANGATDWATFRIISYDTAEKTWVEHCVGSVRAETGPPDLCVNTALRKQCAEPVDIAQMYHGFTAAGMDFGENLRNIQAMKVSPDRTACTATITAPSIAPQAHDQYPLHPCSFESILHALLYLCEASQSPMVTNYIEEVVIVNPNDTGAREFESFARRQRTSATTWTCDVSITTNVGDQDIQIKGLDLVQLPANNDDAVDAESFYTVNWRPDVKLLASADALHNSAPVDAAQHLPTFDEHEGYQLASAIFLQEAKEYVTRTGLPPLPTHHQAFMDWMEEEYQSINNGTTPLLDKSLLDGIRADPDRRKSLLDRVARQSARGELLVRVGTRMIDILEQKIDCLEVMFGPDNLMERTYEEGLPGQIAPAVAGYLHCLAHAQTGIKILEVGAGTGSATKVMLDSLRPTEAQDGGGLVSSVSSYDFTDISAAFFEKARARFHDWADILRPKLLNIEQDPAAQGFELGSYDLVIATHVLHATADLNVSLKNIRALLKEGGDLIVIENIQPKFMCSQLPFGLLPGWWRSVEPYRKTNPLILKEHWTEELQNAGLRPRLIINDTDDGINEMSAFVASPMPKVLDGSQPCSIIYSSTYPGQQQLALEVADRLPRSCTAAVVDLADISLDHSDTVGIVLVGCQGLDLSELTSSEYDRVKFILTSFQKLLWVTCDPTDVPKSALATGLVRSTRWEREHDNVNIILLSVSLSRPTPLTISSEIVRLCENAFISCKRVPPNSEYRIEGSNGVLLTNRLFPAAGINECIGLGSRPRSRQVPLGTVDHPIKLTSIGSQQPNGFHFIEDPQAHEPLDPDEVKIRIHAAGLDEEDADQLSRLIPGHGFGDQGSGTVVEIGHGVQGIQVGDQVMALRTGPSCALQTFFRTHSATVAKIPDGIRLSDAAALPLPWVTAYHSLVTVARLDSQEKVLIHPAIGATGQAAVQVASMLGATVYATVETDAQRQTLAEYGVEESHILDSASVEKQFGTQTSTQGVDVLLNLRRDGLEFLHLSCLSPFGRLVDISGSRAFPSQVNSPSNQSYYRVNMRELSQLKPESIRQTLRTVAQLLASPTIRPVAPFRVGYSQLQRVLSEIRRGSRGPWVIQPLPNDPIPPLGSHQFDPSASYLLIGGFGGLGRSVARWMHHRGAKHFIFFSRSGASSAAARELCADLRAAGCAVSDMICDTTDAQAVAKAMAQCEASMPPIRGCLQASMVLEDSMLSNMDHTRFLGAITPKVQGTINVASALAPIKSNLDFFVMLSSSAGIVGNRGQANYAAANTFLDAFAGQLVTQGYPATSVSLGSVLSVGWVAENQHKLRIAFAFGALSEDLLLSILEYHMDPAWGAAQSIQTCHTVVGVRSARDFQRQSIPLPGFMAHPLFSPLLAIAGRSQTAEQAAEAPVSQGLREASSMEAAVEVVTRAIVHKLARIMALSVQEIDPQRSLGSYGVDSLVTVDLKAWFQREVGVSIGSGELLGEMAMTQLAQQAADASQFLPAELRGKLRKNTDIHV