The following text describes a protein:
Function:
Nonribosomal peptide synthetase; 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. OtaB is responsible for the linking of phenylalanine to the dihydroisocoumarin ring (By similarity). 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:
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, epimerase (E) domains (responsible for L- to D- amino acid conversion) are present within the NRP synthetase. OtaB has the following architecture: A-T-C-A.
Sequence:
MDLRTGYMFPCLTDGQFVEDDTLHSVALGIDSPISLSNGPDGEWARELSIAWAILLFTYNEQEAVEFACLRNQHWFCVDAKMNRDLSWKDIEIHEGGTSDGRQVNTGLCLSQEGATPIPTRLQLVLVGSISGGGLSLEYRPNLLSAEQAANVASTLETIMRALQGRTVSIGSIDVLSERNITDLNRFAVARRALPEGCLDDIITAQAVERGNSIAIDSWDGTLSYQELDTLSTLLAKYLRSLDLSGTYVPLCADKSAWAVVAMLAILKAGAACSPLDPSHPRSRLQSMVQLCDAKAVIATERHASLLQMDGVEVVVVGPDMSSFLQHQISPAEAPGPSHRDVAFLMWTSGSTGAPKGVILEHTALFMSISAYAAANQFSAETRCFQFTSFTFAVSLCDIFGTLSQGGCLCMPSETQRLTDLTGALRELHATFCWLTSTSLADLNPHDLPDLRSVTVGGESLSRELVARWATHLRLTVSYGTTETAGWCLLNTGLSPTGDARTLGRPTIPGVWIAHPDNVNRLVPVGAVGELLVEGPFLAQGYLDDEERTAAHFIPPPSWMTQFRPQEVTRLYRTNDLVRYNSDGSVSFVGRRQAHAKIRGNRISLPEIEAQVRHSCKDAQAVVELVTTKDQVEMLTAFLVVSGQESLSEAPLICPPNDCFRETVTNSLSVLEQSLPSYMVPTVFVPLSHIPLTRTNKADRHVLRKLAEAMSRADLVQLMTKPRPVEQLPLSPLERQIQGLWADLTNIPAESIGPDDNFFHLGGDSVLAIHLVPLARRHGLSLTVQDVFRYPKMKELGAHLEQEASQGSQRSKSQPIASFDPTPWKSVAAQQCGIDELAIEDVYPCTALQEGLMALSAQRTGAYILSMAQNLSPTVDLGRLLEAWQTVVKAVPILRTRIVRLTNEGFHQAVVDESIEWQSVKSEAEFRRMNQLNPLGLGTRLVRFALLLSAADQPSRLLLAMHHSVFDRWSGPLLVRAVEDAYQGQPVMPQYFKDFVSYVSTCPREEVDAFWRHQLSDADPTVFPPTPEPNYLPSPTKSSERIILLPLSRTHVTITTKLRLCWALVLSQHTGNADVVFGAVSTGRSARVEGIESLIGPTLATVPFRVRIDGSAMVSDALQALQDDAATMLPYEQRGLQNIARISRETRAACNFQNLLIVHAPDSRGHSTILKITDDQQLLDLFSYGLTLSCEVLDQDRIQCQAFFDPNMLEHAYVKVLLDQLAHAVRQIHAVPDCKVGEISLLSPQDQQQLQEWNPPIPRTGLTIHETIQRQCLAHPQKEAVCSWDGSITYRALNELSSSLASQILQRCGQPTSFVPLLMERSKWTAVTMLAVMKAGKAFVLLDASFPVERLQSICCQLDATLILSSSKHADVAQRLVSNPLIVDAIIGLPGPSLALPVVHPDATLYAVFTSGSTGRPKAVLISHASYGSGAEAHIPAALITPATRVLQFASYAFDASIIEHLSTFMAGGCVCVLSDPERTSSLAEAVAAQRANFAWLTPSVTRFIDPQDFPTMDRLCLMGESMRRSEIERWSSRVNLMQAYGPAECSVLATLRPSLTTQSDPRNIGCARGCHAWVVDPENHTRLLPIGAVGELIIEGPIVGQGYHGSPEQTQAAFPPVPDWLSDYHDGDLSQVRVYKTGDLVQYSPKLDGSLLFIGRKDRQVKLRGQRLELSEVEYHAYHTLAGTWELVVELINSQHNPALALFLAEKQDSPKPCGVLSMTPAWRSVMSRLRDTLASRLPPYMVPTVWIPITQIPLSSSQKTDRRSLQSLAGDLSAEQYQTYILASSSEATPGLTHSHLKEVPLNENELVLQDLVRQVFTGEDGSLSVASIPMDGLFTDIGGDSLGALALTSLAKQHGFHFTAGDVLGSSLGELASLRHT