The marine bacterium Phaeobacter inhibens secures external ammonium by rapid buildup of intracellular nitrogen stocks - PubMed

Figure 4.

Biosynthesis of antibiotic TDA during ammonium depletion in P. inhibens DSM 17395 (see Fig. 5b). TDA biosynthesis is closely intertwined with the biosynthesis of amino acids (Phe, Ser, Cys) and with assimilatory sulfate reduction, thus requiring an integrated cross-regulation of carbon, nitrogen and sulfur metabolism in P. inhibens DSM 17395. TDA biosynthesis drains phenylpyruvate from Phe anabolism, proceeding via the conventional shikimate-chorismate pathway. Phenylpyruvate-derived phenylacetyl-CoA is then transformed via epoxidation and isomerization (oxepin-CoA forming), followed by ring cleavage to 3-oxo-5,6-dehydrosuberoyl-CoA (Teufel et al.2011). The latter has been proposed to be converted to the seven-membered tropone carbocycle, ultimately receiving reduced sulfur from cysteine-derived S-thiocysteine (Brock, Nikolay and Dickschat 2014). Boxes indicate the time points (15, 20, 25, and 40 h; Fig. 1) for cell harvesting and their different colors reflect (i) relative changes in abundance of identified metabolites and soluble proteins (D; determined by 2D DIGE), as well as (ii) identification metascores for soluble (S; determined by shotgun analysis) and membrane (M) proteins. The complete dataset is presented in Fig. S8, Supporting Information. Compound abbreviations in alphabetic order: 2-OG, 2-oxoglutarate; PEP, phosphoenolpyruvate; 3-PG, 3-phosphoglycerate; TDA, tropodithietic acid. Enzyme names in alphabetic order (identified: blue font color; predicted: grey font color): AroA, 3-phosphoshikimate-1-carboxyvinyltransferase; AroB, 3-hydroquinate synthase; AroC, chorismate synthase; AroE, shikimate dehydrogenase; AroH, phospho-2-dehydro-3-deoxyheptanoate aldolase; CysE, serine acetyltransferase; CysH, phosphoadenosine phosphosulfate reductase; CysK, cysteine synthase; IorAB, indolepyruvate oxidoreductase; PaaACG, proteins involved in phenylacetate degradation; PaaZ2, oxepin-CoA hydrolase/3-oxo-5,6-dehydrosuberoyl-CoA semialdehyde dehydrogenase (NADP⁺); PatB, cystathionine beta-lyase; PGA1_c00590, chorismate mutase; PGA1_c07640, O-acetylserine sulfhydrylase; PGA1_c20760, putative nitrite/sulfite reductase; PGA1_c24800, putative bifunctional SAT/APS kinase; PGA1_c30200, prephenate dehydratase; SerA, 3-phosphoglycerate dehydrogenase; SerB, phosphoserine phosphatase; SerC, phosphoserine aminotransferase; TdaA, transcriptional regulator, LysR family; TdaB, putative beta etherase; TdaC, conserved hypothetical protein, similar to prephenate dehydratase; TdaD, thioesterase superfamily protein; TdaE, acyl-CoA dehydrogenase; TdaF, putative flavoprotein, HFCD family; TyrB, aromatic amino acid aminotransferase.