The following text describes a protein:
Function:
Nonribosomal peptide synthetase; part of the gene cluster that mediates the biosynthesis of the aspoquinolone mycotoxins. The first stage is catalyzed by the nonribosomal peptide synthetase asqK that condenses anthranilic acid and O-methyl-L-tyrosine to produce 4'-methoxycyclopeptin. AsqK is also able to use anthranilic acid and L-phenylalanine as substrates to produce cyclopeptin, but at a tenfold lower rate. Within the pathway, 4'-methoxycyclopeptin is then converted to 4'-methoxydehydrocyclopeptin by the ketoglutarate-dependent dioxygenase asqJ. AsqJ also converts its first product 4'-methoxydehydrocyclopeptin to 4'-methoxycyclopenin. The following conversion of 4'-methoxycyclopenin into 4'-methoxyviridicatin is catalyzed by the cyclopenase asqI. 4'-methoxyviridicatin is the precursor of quinolone natural products, and is further converted to quinolinone B. The prenyltransferase asqH1 then catalyzes the canonical Friedel-Crafts alkylation of quinolinone B with dimethylallyl cation to yield dimethylallyl quinolone, which is subjected to FAD-dependent dehydrogenation by the FAD-linked oxidoreductase asqF to yield conjugated aryl diene. The delta(3') double bond then serves as the site of the second alkylation with DMAPP catalyzed by the prenyltransferase asqH2 to yield a carbenium ion intermediate, which can be attacked by H(2)O to yield a styrenyl quinolone containing a C3'-hydroxyprenyl chain. The FAD-dependent monooxygenase asqG performs epoxidation of the terminal C7'-C8' olefin. Finally, after dehydratation of the epoxide at C3 by asqC, the quinolone epoxide rearrangement protein asqO catalyzes an enzymatic 3-exo-tet cyclization to yield the cyclopropyl-THF ring system in aspoquinolone (Probable).
Domain:
NRP synthetases are composed of discrete domains (adenylation (A), thiolation (T) or peptidyl carrier protein (PCP) and condensation (C) domains) which when grouped together are referred to as a single module. Each module is responsible for the recognition (via the A domain) and incorporation of a single amino acid into the growing peptide product. Thus, an NRP synthetase is generally composed of one or more modules and can terminate in a thioesterase domain (TE) that releases the newly synthesized peptide from the enzyme. Occasionally, methyltransferase domains (responsible for amino acid methylation) are present within the NRP synthetase. AsqK has the following architecture:A-T-C-A-M-T-C.
Sequence:
MAVSYTNFTNLPAKLYLVYRACTFTPLHAENLASNITQAMKQLLAQPDACVKDIDIFSPFNEITVSRWNAEIQEAPDASLLEVIRGHSRYRPSHTAIHAWDGTVSYSELDVTSTKWAIYLQSQGVKAGCLVPIMMDHSKWAVIGQLAILKAGGAFVPLDPGQPLFRLENIVRLTTESHISLSSPHLANRLHGLVETVLVISDERTESLPKANAHHDAADISPVVNNGPAYVLFTSGSTGRPKGCVVGYGALSDVVNQTTALKIGPDSRVLQFASYTYGMSLIEIYCTLAAGATICVPSEDDRLNALSSILLSMQVTWAILTPSTTISIADAVVCLNTLVVAGEALTMDRLHSLADKTEVIQAFGLTEWAGICCVSQRITSETDLRVIGRSHTARLRLVDPANYNRLAPVGAVAELLIEGPAMADGYLGDPEQTARAFPKTSTGGRFYRTGDLVQYAADGSLRYVSRKDSQVKIRGMRVELTEVEYQIRRAFPGVEEVVVEAAAPKNSSGIPILVAFLCPEDLSGLVCTIKETMKRSLPDYMRPSVYVPLEFIPKTISRKVDRKALRHLVQSSTRHELERYTQASLPSLVGPRTNIEQLVHELVADMLRLDPLSLGMRQNFISLGGDSVTAMLLVNKLRRKGYKITVAAILRAQSLLDVASLVHYPAGLEPSAQKSTPGDLKLVPRAIHRISDSGTVEQSFSQARIWFLQTLRPSSTWLLLPSATRLRGSLRVDALETAFSALVERHETLRTTFEDREGSGVQVVAPFHPYQLEIIEIPSGSDADLITALHGQQIRPMDLTKECWRATLFRLSPDEHVLNIVLHHIICDGWSFDIFLKTLQIYYAAALQGHSPLEGVEPLPIQYRDFSIWQRQNKARTSVEQLAYWVRQLDGSQPAEFLCDKKRPHMLSGKAGSQPVKIDVCLYHDVKRFCSMKHVTPFTVLFAAFRATHYRLTGASDATIGIPSVSRPQAELEELIGYFGNVQCIRTKVESCSSSFQLLVHQVQSSITAAFENQDVPFDQIVSKLLKDRDVSRHPLVQVAFILHTQAQFGKLRLEGLESEQLPLPHVSRLDLEFHLYPGEGGGDLQGEVLYSMDLFHAETINAMVLVFYDILREGIRKPDTSIDSLPFPGGYSILNERGLIYPQQSRSLSIIDLFDEQVRAQTDEVAVKDINGHLTYSELHKRSSMLSAWLKNSYSFAEETPVGVYASRSCESIVAILGILRAGLAYIRLDIDAPKARTEMILSCLPNCRLVLVASGLEPPRVCVQGVQFAYIADSCKETVTDVHDFLKTCTPPGPMSLAYIVFTSGTTGTPKGVMIEHHGVANLAKEPDIIAHAVNSRIASHMLNPSFDASGFEIYATLLNGGTLVCIDNSVVFDFPALGATFIQHGIRRAFMTPAILKQTLASCNSLLRMLDILYVGGDKLDPGDVAKVQRLTTGRVQIFNCYGPTENSIVSTKYRVPVDEEGVNGVPIGRSISNIGAYVVDRSLRLLPLGVLGELVVTGPALARGYIDPKHDIGRFIELDISEEVAPMRAYRTGDMVRYRPRDAQLEFFGRMDQQVKVRGYRVELAEIDNTLLLSPFISAAVTVARQDQELVSFVTVSDMASGFNDRAETEHVDSWLDVVEGEDYYGSVGTIEPHSLGADFLGWISMYDGEPIDKNDMREWLQDTITAILSCSPSSVLEIGTGSGMILFNIIGSIQKYVGLEPSPRAVDFVRRAVHWVPEAAGKVNIKCGTASDIGRLQDMGTLDLAVINSVAQYFPSLDYLRNTIKDLVRQGVKSIFLGDIRSYALYQEFQVSKVLRLYGRGLTITRFRQHMAEIARLEKELLVDPAFFTSLPAELPGMIEHVEIWPKRMKATNELSCYRYTAVLHVKRAEQPLLIREVKEISWADFQAKGWDYNSLSQMLEISDASTVLAVENIPFKKTIVERDMVRLLQELPEDTGSVSWSSNARGPKRALAPIDLFDVAKKTGWDIEISWARQRSQRGGLDAVFHRQGPRVLFRFPVDPYIPGACSNDPLSPQRNRLLEKHLLEYMSTKLPTYMVPKLIHVLDKMPINNIGKVDRHVLAQRAAITSATISESESLFRREIEPAFTSEIERAVWEEFTGVLGREVGVADSFFRNGGHSLMAIRLVSRINKRLSSALSVSELFRYPTVSGLAQHLQGLGALETRAVTVYAPFSLLDRPYDPSEVRLPPEADIVDVTPVTECQAWFLQCWSLVSHSFIIHGVLDVDRLRAACQAVVRHHPPLRTVFTEFQTQLVQAFDGVSLSAILYDIARAYGNSASPLSNAVPFSHHLHMCRSTRPDALAFWKAYLRDAVLTEVPRPEEVNATNEKPLEIIQQEALGEVSLPSTVDITFSTLVNAAIALALARLVQRNDVIFACVMTSRGVLAELAESVVGPCVNRCLLRVKVPDDSNPDSTALDFCRNLRDNQAQVSGHGHLGFRDVVENCTSWASLGVDVGRIAFVTHLPAETALETFSLTLLDSPVSYDSTNVTINPGNQILVRSAITDEQQACIQVLSSSNVMGAEKALFLANRILMIAQRLSVSVSGGRSPRLLELDK