Function
Highly reducing polyketide synthase; part of the gene clusters that mediate the biosynthesis of the host-selective toxins (HSTs) AF-toxins responsible for Alternaria black spot of strawberry disease by the strawberry pathotype (Ref.1). AF-toxin I and III are valine derivatives of 2,3-dyhydroxy-isovaleric acid and 2-hydroxy-isovaleric acid respectively, while AF II is an isoleucine derivative of 2-hydroxy-valeric acid (PubMed:15066029, Ref.1, PubMed:22846083). These derivatives are bound to a 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid (EDA) moiety (PubMed:15066029, Ref.1, PubMed:22846083). On cellular level, AF-toxins affect plasma membrane of susceptible cells and cause a sudden increase in loss of K(+) after a few minutes of toxin treatment (PubMed:22846083). The aldo-keto reductase AFTS1 catalyzes the conversion of 2-keto-isovaleric acid (2-KIV) to 2-hydroxy-isovaleric acid (2-HIV) by reduction of its ketone to an alcohol (PubMed:15066029). The acyl-CoA ligase AFT1, the hydrolase AFT2 and the enoyl-CoA hydratases AFT3 and AFT6, but also the polyketide synthase AFT9, the acyl-CoA dehydrogenase AFT10, the cytochrome P450 monooxygenase AFT11 and the oxidoreductase AFT12 are all involved in the biosynthesis of the AK-, AF- and ACT-toxin common EDA structural moiety (PubMed:12019223, Ref.1, PubMed:18986255). The exact function of each enzyme, and of additional enzymes identified within the AF-toxin clusters have still to be determined (PubMed:12019223, Ref.1, PubMed:18986255).
Sequence
MDPQQRLLLETTYEALENAGIPQANTNGSNTSVHVAMFTRDYDRNVYKDTVGIPKYQVTGTGEAIMSNRISHIFNLHGPSMTIDTGCSGAMTAVSQACMSLRSGDCDIALAGAVNLIMSPDHHISMSNLHMLNAEGKSYAFDSRGAGYGRGEGVATIVMKRLDDAVRCHDPIRAVILDAVINQDGYTAGITLPSSEAQAQLERKALNRVGLKPQEVAYIEAHGTGTAAGDAAELDALSSVFCVDRDLPLYVGSVKSNIGHLEAASGMAALIKATLMLENEAIPPSINFSRPKENLRIDERNIKIPTALQPWPKGASARICVNSFGYGGTNAHAILERAPERPTVMGPKNTPYLFLLSAKSRASLSRTVKNIKEWISSQHDTLSLRDLSYTLNQRRSMMSWRFGGVATTHQELLDVLTQELKSSSAVRTPTRANINFVFTGQGAQWPGMGRELLVVRAFKDSLNQSRNVLHQLGASWDLFDELVRDKESSRLKEPQLSQPVTTAIQIALVETFRSFGISPGAVVGHSSGEIAAAYTAGYLSHDTAIKIAYYRGFSAEIAKAKGMENGAMLATDLGEATAREYVAKLVKGKATVACQNSPNSSTLSGDTTAVSELEEMLSKDSVFNRRLQVDAAYHSHHMEAAAEEYEKSLGDVCVEQPLTKVRFFSSVVGREVWEGFDSTYWTTNLTSTVRYCDALQALCRTQFAQPQGEQSHQLFVEIGPHNALAGPTRQSISDLDKQSTYSYMSALVRGSGGVGTILGVLSELIKHGHHVDLAALRTLDPTCQEANVLHDLPSYAWDHSKRFWNESRLSREYRLRKHPYHDLLGLKMTDHTPLRPSWRYLVGVEGLPWLKDHIVDGTIIFPGSGYLCMVMEAAETSFTKALIIPESPSRVELQLNFCPVGPTNGNAFHFVITAVSAAGIWAEHCKGSVEVKYAAANRPRKALDIPVTFDQISEGLDVESEAIEKISSQELYDELSAVGNTYGPMFRGINKAIIQADRSASFISIPDVTRMMPAQYMRPHFIHPTTLDILLHSSLPLVNRQVGQASIMPVRIDELALSTLIQNESGSSLAAITTLTSADLRGGDADILVFSDSGDATDRPVMSVSGLELRRLAPTGQPATSGTARDICYEMKWDADVEFISAEFLRPQKLPPSVKQKWDVIDRATDIYIQRCLQHLGKRALDASGDHHKLLVKWMNSTVAKTQTCEDPTEAKILEMSSSQGVEGEFLARLGPALPEIITGKVNPLQLMLEDGLLYRVYADDSSKRCYDLMAGYLNSKSFKQSGFAVLEIGAGTGGATLPFLQSLDHNGNRPVVFDFTDISAGLFESAKERLQDWSDVVNFRTLDIEKNPKDQGFTEGFYDIILACNVLHATSSVDSTLSKVRQLLKPEGVLLLLEVTKPRHYHNVTFGTLPGWWKGVNDSRAAGPLLSPEGWSTRMRKASLNMQLAVYDDNETPISSLIVAKPIQEVTKKKQVQIVLDSSVPIWLRKFADQVLSRLAAEEFGVSLTSWDEMTVNPHDSSIWLVIDNGEHPVLSHVTPIQLQSVTEMLKAPSHVLWISVVHDPQFSENPFKHLITGISRTAHAENDRLKMITVDVQQSICQEEGKEEGNRFMSFLMGVVISLSKADLLTIEREYVYKNGQVNIPRVLPSPDIQGWMPGNVTGLPEMKPFHDSQKAWILDIERSEFMKMPVFTENDAFRESLDENEIEIDVEAIGVPELLIRHSINGFAGRVIAIRSKVDGIKVKDNIVAFAASSYPNRLRVHQSQARVVPQGVSSRIAAALLIPLMAVSHALVNIASTNSPIVLIHGATGTIAQSSVAIAKALGSVIIQTVSGDVESPALDDVVSTFADHVVPDQGYSSKHQLQKVLRQRKVDVILSFSKNRVSKEVAGTLKPFGHCIHIENGPKPSLQIEQSQYLSNATISRFRMDAVVRAQPEAVAFAFSTVIDALGSSKMDSKAVNVVSRPVGELDRLFKQEYQHHRNESTVLHVDDCLVRVWSSEKRSLSLDSDATYVVSGGRGDLGKRFIRLMCAAGARHFVTLSRGVSSSHTQLTSLQTELQENVRNDCVLQDIQCNIADLNEVQNALAIIKTQGLPPVRGIIQAAVALEDSTMNSITSDSFNRVLGAKAHGTMNLRNTFAPEGLAFFISLSSAVTVIGTSGQSSYNAENSVQDALAQFSNRDGCHYMSLNVGTIEGADATADNQTRVQALRRQGLISITPDELLGFFRYSVTSEARKGHRCRQAIIGFTPESLSLTTAANGTVHSPMFTHVRERGDRKTSEKRSGAKKTFKATIQETRDFEKISQLMALWIGEKVANLVAADASEVDLGSSIADFYVDSLIIIELRNWINRELQASIFIPETMESQNLLSLGAKVASRSALVPSSISSKVSNSNDEALSIDSTASLSLAPSSQPPEMLETPYAQLQHLPAADLHTALDMLIESRKGFCTQAELEETLRASAEWRGVEKADRDAIVSKFTGSNLRLESYEKALHLERREPLQDHAVFYLGHITDQVPDHTQAERAAIIVHSTLSFKHQLEMGVLEQNSLNGSPLCMSTLQWLFHATQEPRHELDVMKKYRASGNVAIMRRGHIFVATVHDDDGLAALVALFEDVIQHSEDAIPALSILTSHRRDDWAQLKGSLESITGNAAKLEAIQSAAFVICLDEGAPTNPGERATSQLLNDRHLSNRWLDKTLQFSVAANGVSSLIGLNSTLDGLSVKQLHEAITEQILASTRGHMDILHQDHERRPAKRLSVFRELGFEIPPPITTAIEEKRLRNLAHYPSVAAFSQHYADLNRTFLGTRRLRSKGTVLMAIVFAIRLFYGRFEPVWETVTLAKYARGRTDWLQIVTPDVMEWIESAIQRNSGGKSTICGRDMLVQLQASTTKHTQNVRQVADSRGFVEPLYAFQAFIESEGRKLPRLFKSEAWKHSDRNATPKLVKTDCLGSGGWLRMQEAGFLMPHPNSLFIHYEVHHTDPLVLVQGRDRDVAKFSGCLNEAVKAMRTIIEQSS