The following text describes a protein:
Function:
Non-reducing polyketide synthase; part of the gene cluster that mediates the biosynthesis of elsinochrome C, a perelyenequinone phytotoxin structurally similar to cercosporin. The first step of elsinochrome C biosynthesis is performed by the polyketide synthase elcA which catalyzes the formation of nor-toralactone. The starter unit acyltransferase (SAT) domain of elcA initiates polyketide extension by the selective utilization of acetyl-CoA, which is elongated to the heptaketide in the beta-ketoacyl synthase (KS) domain by successive condensations with six malonyl units introduced by the malonyl acyltransferase (MAT) domain (By similarity). The product template (PT) domain catalyzes C4-C9 and C2-C11 aldol cyclizations and dehydrations to a trihydroxynaphthalene, which is thought to be delivered to the thioesterase (TE) domain for product release (By similarity). The bifunctional enzyme elcB then methylates nor-toralactone to toralactone before conducting an unusual oxidative aromatic ring opening. The next step in perylenequinone biosynthesis is an O-methylation at the nascent OH-6 of the elcB product performed by the O-methyltransferase elcD. The oxidative coupling of the two monomeric naphthol units in perylenequinone biosynthesis is catalyzed by the FAD-dependent monooxygenase elcE and the multicopper oxidase elcG. ElcG might catalyze the first intermolecular coupling in a regio- and stereo-selective manner via a phenol radical coupling mechanism and the elcE could forge the second C-C bond intramolecularly via a hydride transfer mechanism. The fasciclin domain-containing protein elcF might also play a role duting this step (Probable). The last piece of the puzzle in the biosynthesis of elsinochrome C is the additional annulation by enolate coupling to afford the dihydrobenzo(ghi)perylenequinone system, catalyzed by the FAD-dependent monooxygenase elcH.
Domain:
Multidomain protein; including a starter unit:ACP transacylase (SAT) that selects the starter unit; 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 product template (PT) domain that controls the immediate cyclization regioselectivity of the reactive polyketide backbone; 2 acyl-carrier protein (ACP) domains that serve as the tether of the growing and completed polyketide via its phosphopantetheinyl arm; and a C-terminal thioesterase (TE) domain that facilitates the release of the final product from the enzyme.
Sequence:
MKHVSAPPPVLDELLKTTALSKAIKFDLPITAPYHAPHLYTAENVNTILCGVDDVVATTIIPIVSSSTGTVVTSATFRDALRVAVEACLQLMIRSDLIAPGIASHVQHADGFAIRHIATAPDGLALAVQTALSQAGGRSQSGRVNAPDQNDTTSIPNALSTPRAKAKIAILSMSGRFPQAPSMEAFWHVLENGIDTHELALASRWNTRTHVGDLSLKELPKNTSGTGFGCWLHDAAQFDARYFNMSPREAPQVDPAQRLALLTATEALEQAGIVPGRTSSTQKDRVGVYFGSTSNDWMETNSAQNIDTYFIPGGNRAFIPGRINYHFKFSGPSYTIDTACSSSFTALHLACNALWKGEVDTAIVGGTNVLTNPDMTVGLDRGHFLSRTGNCSTFDDGADGYCRGEAVATLVLKRLDDAVADKDPVQACILAIATNHSAEAASITRPHVGAQQDLFASVLADAGVKHTDISYCEMHGTGTQAGDAGETTSVLQSLAPIEPPNAVRKQHQPLYIGAAKSNVGHGEAAAGVTSLAKVLLMLKKSTIPPHCGIKTKINHKLPDLPSRNTAIAMEAVSWPRPVNGKRQVLLNNFSAAGGNTALILEDAPEVPTLDVPDIRQCHLVAVSAKTPASLENNVKNMLAWLDEKSDASNLTLARLSYTSTARRIHHPHRVMINATSLDSVKASLRTALDLKKGSSRPKGTPRFVFAFTGQGAQYAGMGADLFAQFTGFRADISRYDQICRQLNFPPVRQLFEDPTTFCDATPTTLQLAMVCFQMALYRMWVTLGVTPSAVVGHSLGEYAALYAASVLTQADVINIVGSRAQLLEKHCEQGSHTMLAVRSNAEDLEAALGPSGLTYELSCHNGRESVVLGGTKSQIETIRPTLQRSRMSNRVLEVPYAYHTSQVEPILASLAAVARGVHFAKPAIPVISPAFGTVLTQSEDFGSDFIVKHCRNKVNMLGALQAARQMSLLDEKMMGIELGPEPVVIKMVKEVAGPAFQTFASSRKDEPALNILASALSAFYTAGTDVKWTAYHADFPSAQVVLELPAYAWDLKEYWIQYVNDWSLRKGDAPLVIERTTLEGTCIHKVVSNSLGVSGGELLVEADLSREDLHPMVQGHKVYGVPLCTPSVYADIALTIGEYAKQFSGEGSTKLGVEIANMNIQSALVATSDGKPQMLRTHASYDAKQKSLYCTFSTLDDAGKVKEQHSNCLIKLFDVEAARTALKSSAPAIKSRISILQLQLNEFGNTFRYSKAMIYKMVGQLADFDPKYRALEEITLDSDALEALGRVNFTKVSAEGKFHTNPAYIDALSQLGGFVMNGNEGVDLDKELFVNHGWASLKLLEAIDPTKTYTTHVKMTEGTDKLWTGDITILDGEAVVGVFGGVALQGVPKRLMSYIVHAASKRTNGVAPRTAGEPQTQRVTAPEVVSAVVKTTTKQLVTQAPVEDRSITTAISIISQESGVEAADLTDDTSFDDIGVDSLLGIMVSSRIRDELGIDVDSAAFLEVRTVGSFKTFLRGLTGTTEQFTTVTKTVTKEITPTELRESSFAQSAVAGDSFGVWTNVLAILAEESGIDVSDLTGDTYFSDIGVDSLLSLVVVSRLRDEFDLDLPEQSLFIDYPTVASLKARITGCTRSPSVFSDSDATTDVPSVFSPSLEVETTSEDFQPLAFSKKEALVAVAEVALTPLEKADPFMSIGLASYVESLQRHQPHGPYHLAGWSAGGVLAYAVAQELMATGEEIATLTLIDSPPPTDGLDRLPRRFFDHCSAVGIFGGEMSAINPSNKRAKLPEWLMPHFEATIELLHDYCAPPMPLTTNAPKKINLIWAGGCAFGGKYAPLPPASMVGEDTEGMKFLTEQRTDFGPDKWTDLFPGRHIDIDVVEGEHHFSMMRGKGAQQLGGFLRKTLGLLA