phnB

FAD-dependent monooxygenase phnB

409 amino acids

FAD-dependent monooxygenase; part of the gene cluster that mediates the biosynthesis of phenalenones such as herqueinone, compounds that have been reported to treat tumors, bacterial infections and/or mycoses, and rheumatic diseases (PubMed:26978228). The non-reducing polyketide synthase phnA synthesizes the heptaketide backbone and cyclizes it into the angular, hemiketal-containing naphtho-gamma-pyrone prephenalenone. The product template (PT) domain of phnA catalyzes only the C4-C9 aldol condensation, which is unprecedented among known PT domains (PubMed:26978228). The transformation of prephenalenone to phenalenones requires an FAD-dependent monooxygenase phnB, which catalyzes the C2 aromatic hydroxylation of prephenalenone and ring opening of the gamma-pyrone ring simultaneously. Subsequent intramolecular deprotonation of C3 phenolic oxygen accelerates phenalenone ring closure to yield the tricyclic phenalenone core with a C2 hydroxylation (PubMed:26978228). The remaining tailoring enzymes encoded in the gene cluster involved in the biosynthesis of herqueinone include the O-methyltransferase phnC which can methylate C2-OH to stabilize the northern portion of the phenalenone core, the prenyltransferase phnF, which installs the dimethylallyl group at C5, and the oxidoreductase phnG which can further hydroxylate C6. Formation of the fused tetrahydrofuran moiety may require an additional enzyme and may involve those of unassigned function in or immediately adjacent to the gene cluster (Probable).

Belongs to the paxM FAD-dependent monooxygenase family.

44.641 kDa

MTSPQTHVIVIGAGITGLLTCQGLKKAGISYSCFERDTSLNSRSNEWTMAIHWSLPLLAEILPTEVRAKLATIACNPVAGIHSGLYPIIHGETGDLITGVPYKDGLRVPRSKMRALCAEGIDVQYGKTLADVAFNESGNGVVATFTDGTLVAGTMIVGADGPRSRVRETAMGDAKLAATTSFPIFHTNMTVCYNDAEKAKFVREKYPTSYLALSERSFHAFQSISSMPDGPDHPETWVFHMAMAWMGQSDNAMCYAERLALVKSKAEGLGEPARSAFMWMPEETEVHKADISYWISQPWNNRDGRLTLVGDAAHPMPPYRGQGLNHCICDVSKLLAGLAGVHSGSTTLSDAIQEFEAEMIPRGKEEVTCSVENGKMLHDWNKIQESPVFKRGFLPMDGHDTRKEIAQAS

phnB

Cis-3,4-dihydrophenanthrene-3,4-diol dehydrogenase

277 amino acids

Involved in the degradation of phenanthrene. Catalyzes the oxidation of cis-phenanthrene dihydrodiol (PDD) to yield phenanthrenediol. It can use either NAD or NADP as electron acceptor, however NAD is preferred to NADP.

Belongs to the short-chain dehydrogenases/reductases (SDR) family.

28.827 kDa

MAWLEGQSVFLTGGVAGLGRALVKRLVEEGANVTVLDRNARGLDELVESFKGRVAGSPGDVRNLADNRKAVELAVERFGKLDTFNRQRRHLGLLCPPCRPAGRCHQRSFDEVIGINLMGYVMGIKAAAPALVRSRGSVILTLSSSAFYAGGGGVLYTVAKHAAVGLIKQAAHELAPYVRVNGVAPGGIASDLRGPKSLGMGEQSITSVPLADLVKDIAPIGRLSDTEEYTGSYVYLASARNSAPATGVIINCDGGMGVRSVLGPASGGKGLLEKFGG

phnB

Anthranilate synthase component 2, pyocyanine specific

200 amino acids

Part of a heterotetrameric complex that catalyzes the two-step biosynthesis of anthranilate, a precursor for Pseudomonas quinolone signal (2-heptyl-3-hydroxy-4-quinolone; PQS) production which is required to induce the genes for the biosynthesis of the virulence factor pyocyanine (PCN), a characteristic blue-green phenazine pigment produced by P.aeruginosa. In the first step, the glutamine-binding beta subunit (PhnB) of anthranilate synthase (AS) provides the glutamine amidotransferase activity which generates ammonia as a substrate that, along with chorismate, is used in the second step, catalyzed by the large alpha subunit of AS (PhnA) to produce anthranilate.

21.845 kDa

MRITLLDNFDSFTYNLVEQFCLLGAEVRVMRNDTPLPTIQAALLADGCELLVLSPGPGRPEDAGCMLELLAWARGRLPVLGVCLGHQALALAAGGAVGEARKPLHGKSTSLRFDQRHPLFDGIADLRVARYHSLVVSRLPEGFDCLADADGEIMAMADPRNRQLGLQFHPESILTTHGQRLLENALLWCGALAVRERLRA