The following text describes a protein:
Function:
Lovastatin nonaketide synthase; part of the gene cluster that mediates the biosynthesis of lovastatin (also known as mevinolin, mevacor or monacolin K), a hypolipidemic inhibitor of (3S)-hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase (HMGR). The first step in the biosynthesis of lovastatin is the production of dihydromonacolin L acid by the lovastatin nonaketide synthase lovB and the trans-acting enoyl reductase lovC (called the lovB-lovC megasynthase complex) via condensation of one acetyl-CoA unit and 8 malonyl-CoA units. Dihydromonacolin L acid is released from lovB by the thioesterase lovG. Next, dihydromonacolin L acid is oxidized by the dihydromonacolin L monooxygenase lovA twice to form monacolin J acid. The 2-methylbutyrate moiety of lovastatin is synthesized by the lovastatin diketide synthase lovF via condensation of one acetyl-CoA unit and one malonyl-CoA unit. Finally, the covalent attachment of this moiety to monacolin J acid is catalyzed by the transesterase lovD to yield lovastatin. LovD has broad substrate specificity and can also convert monacolin J to simvastatin using alpha-dimethylbutanoyl-S-methyl-3-mercaptopropionate (DMB-S-MMP) as the thioester acyl donor, and can also catalyze the reverse reaction and function as hydrolase in vitro. LovD has much higher activity with LovF-bound 2-methylbutanoate than with free diketide substrates.
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; 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. A C-terminal thioesterase (TE) domain that is often found in polyketide synthase proteins is not present in this protein, but lovB contains insteado a C-terminal condensation (C) domain that has lost its condensation activity, but has gained a novel function that is necessary for release of the final product; Lacks an enoylreductase (ER) domain that reduces enoyl groups to alkyl group which function is performed by the trans-acting enoyl reductase lovC.
Sequence:
MAQSMYPNEPIVVVGSGCRFPGDANTPSKLWELLQHPRDVQSRIPKERFDVDTFYHPDGKHHGRTNAPYAYVLQDDLGAFDAAFFNIQAGEAESMDPQHRLLLETVYEAVTNAGMRIQDLQGTSTAVYVGVMTHDYETVSTRDLENIPTYSATGVAVSVASNRISYFFDWHGPSMTIDTACSSSLVAVHLAVQQLRTGQSSMAIAAGANLILGPMTFVLESKLSMLSPSGRSRMWDAGADGYARGEAVCSVVLKTLSQALRDGDTIECVIRETGVNQDGRTTGITMPNHSAQEALIKATYAQAGLDITKAEDRCQFFEAHGTGTPAGDPQEAEAIATAFFGHEQVARSDGNERAPLFVGSAKTVVGHTEGTAGLAGLMKASFAVRHGVIPPNLLFDKISPRVAPFYKNLRIPTEATQWPALPPGQPRRASVNSFGFGGTNAHAIIEEYMEPEQNQLRVSNNEDCPPMTGVLSLPLVLSAKSQRSLKIMMEEMLQFLETHPEIHLHDLTWSLLRKRSVLPFRRAIVGHSHETIRRALEDAIEDGIVSSDFTTEVRGQPSVLGIFTGQGAQWPGMLKNLIEASPYVRSIVRELDDSLQSLPEKYRPSWTLLDQFMLEGEASNVQYASFSQPLCCAVQIVLVRLLEAARIRFTAVVGHSSGEIACAFAAGLISASVAIRIAYLRGVVSAGGARGTPGAMLAAGMSFEEAQEICELDAFEGRICVAASNSPDSVTFSGDANAIDHLKSMLEDESTFARLLRVDTAYHSHHMLPCADPYMQALEECGCAVADAGSPAGSVPWYSSVNAENRQMAARDVTAEYWKDNLVSPVLFSHAVQRAVVTHKALDIGIEVGCHPALKSPCVATIKDVLSGVDLAYTGCLERGKNDLDTFSRALAYLWERFGASSFDADEFMRAVAPDRPCMSVSKLLPAYPWDHSRRYWVESRATRHHLRGPKPHLLLGKLSEYSTPLSFQWLNFVRPRDIEWLDGHALQGQTVFPAAGYIVMAMEAALMIAGTHAKQVQLLEILDMSIDKAVIFDDEDSLVELNLTADVSRNAGEAGSMTISFKIDSCLSKEGNLSLSAKGQLALMIGDVNSRTTSASDQHHLPPPEEEHPHMNRVNIKAFYHELGLMGYNYSKDFRRLHNMQRADLRASGTIDFIPLMDEGNGCPLLLHPASLDVAFQTVIGAYSSPGDRRLRCLYVPTHVDRITLVPSLCLATAESGCEKVAFNTINTYDKGDYLSGDIAVFDAEQTTLFQVENITFKPFSPPDASTDHAMFARWSWGPLTPDSLLDNPEYWATAQDKEAIPIIERIVYFYIRSFLNQLTLEERQKAAFHLQKQIEWLEQVLASAKEGRHLWYDPGWENDTEAQIEHLCTANSYHPHVRLVQRVGQHLLPTVRSNGNPFDLLDHDGLLTEFYTNTLSFGPALHYARELVAQIAHRYQSMDILEIGAGTGGATKYVLATPQLGFNSYTYTDISTGFFEQAREQFAPFEDRMVFEPLDIRRSPAEQGFETHAYDLIIASNVLHATPDLEKTMAHARSLLKPGGQMVILEITHKEHTRLGFIFGLFADWWAGVDDGRCTEPFVSFDRWDAILKRVGFSGVDSRTTDRDANLFPTSVFSTHAIDATVEYLDAPLASSGTVKDSYPPLVVVGGQTPKSQRLLNDIKAIMPPRPLQTYKRLVDLLDAEELPMKSTFVMLTELDEELFAGLTEETFEATKLLLTYSSNTVWLTENAWVQHPHQASTIGMLRSIRREHPDLGVHVLDVDAVETFDATFLVEQVLRLEEHTDELASSTTWTQEPEVSWCKGRPWIPRLKRDLARNNRMNSSRRPIYEMIDSSRAPVALQTAPDSSSYFLESAETWFVPESVRQMETKTVYVHFSCPHALRVGQLGFFYLVQGHVQEGNREVPVVALAERNASIVHVRPDYIYTEADNNLSEGGGSLIVTVLAAAVLAETVISTAKSLGVTDSILVLNPPSICGQMLLHAGEEIGLQVHLATTSGNRSSVSAGDAKSWLTLHARDTDWHLRRVLPRGVQAFVDLSADQSCECLTQRMMKVLMPGCAHYRAADLFTDTVSTELHRGLRHQASLPAAYWEHVVSLARQGLSSVSEGWEVMPCTQFAAHADKTRPDLSTVISWPRESDKATLPTRVRSIDAETLFAADKTYLLVGLTGDLGRSLGRWMVQHGACHIVLTSRNPQVNPKWLAHVEELGGRVTVLSMDVTSENSVDAGLAKIKDLHLPPVGGIAFGPLVLQDVMLKNMELPMMEMVLNPKVEGVRILHEKFSDPTSSNPLDFFVMFSSIVAVMGNPGQANYSAANCYLQALAQQRVASGLAASTIDIGAVYGVGFVTRAELEEDFNAIRFMFDSVEEHELHTLFAEAVVAGRRAVHQQEQQRKFATVLDMADLELTTGIPPLDPALKDRITFFDDPRIGNLKIPEYRGAKAGEGAAGSKGSVKEQLLQATNLDQVRQIVIDGLSAKLQVTLQIPDGESVHPTISLIDQGVDSLGAVTVGTWFSKQLYLDLPLLKVLGGASIADLADEAAARLPPSSIPLVAATDGGAESTDNTSENEVSGREDTDLSAAATITEPSSADEDDTEPGDEDVPRSHHPLSLGQEYSWRIQQGAEDPTVFNNTIGMFMKGPIDLKRLYKALRAVLRRHEIFRTGFANVDENGMAQLVFGQTKNKVQTIQVSDRAGAEEGYRQLVQTRYNPAAGDTLRLVDFFWGQDDHLLVVAYHRLVGDGSTTENIFVEAGQLYDGRSLSPRVPQFADLAARQRAMLEDGRMEEDLAYWKEMHQRPSSIPVLPLMRPLVGNSSTSNTPNFQHCGSWQQHEAVARLDPMVAFRIKERSRKHKATPMQFYLAAYQVLLARLTDSTDLTVGLADTNRATVDEMAAMGFFANLLPLRFRDFRPHITFGEHLIATRDLVREALQHARVPYGVLLDQLGLEVPVPTSNQPAPLLQAVFDYKQGQAESGTIGGAKITEVIATRERTPYDVVLEMSDDPTKDPLLTAKLQSSRYEAHHPQAFLESYMSLLSMFSMNPALKLA