Aromatic biosynthesis pathway

Exchange of Function in the Aromatic Biosynthesis Pathways Trp and His Pathways... 

Figure 25-1 Aromatic biosynthesis by the shikimate pathway. The symbols for several of the genes coding for the required enzymes are indicated. Their locations on the E. coli chromosome map are shown in Fig. 26-4. The aminoshikimate pathway which is initiated through 4-aminoDAHP leads to rifamycin and many other nitrogen-containing products.

Several natural photoenzymes with activity controlled by light have been reported to date. Among them are DNA and (6-4) photoproduct photolyases, which are highly efficient light-driven DNA-repair enzymes [14, 15], protochlorophyllide reductase, which is an important enzyme in the chlorophyll biosynthesis pathway [16, 17], nitrile hydratase, which hydirates aliphatic and aromatic nitriles to the... 

Inhibits 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS), an enzyme of the aromatic acid and biosynthesis pathway. This prevents synthesis of essential aromatic amino acids needed for protein biosynthesis... 

Enolpyruvate phosphate and n-erythrose 4-phosphate are independent intermediates in metabolic pathways of n-glucose that are not directly concerned with aromatic biosynthesis. Their simultaneous requirement for shikimate formation therefore indicates the first specific, or branch-point,... 

Figure 4.22 Combinatorial biosynthesis manipulation of the aromatic polyketide pathway.

Some microorganisms may resemble the higher organisms in being able to convert phenylalanine directly to tyrosine thus it can occur in Vibrio (167) and Pseudomonas (605) and has been claimed for E. coli (48 but cf. 807). However in Lactobacillus arabinosus tyrosine is formed by a route not involving phenylalanine (20), as is apparently also the case in Aero-bacter aerogenes (605). The direct conversion of phenylalanine to tyrosine is claimed by advocates of the straight-chain pathway of aromatic biosynthesis described later. 

The information at present available is thus sufficient to exclude certain possible routes for aromatic biosynthesis, but is not yet sufficient to reveal the actual mechanism or mechanisms used, or to define parts of the pathway. But it seems probable that the techniques available are adequate to deal with the problem and that perhaps in a short time the present obscurities will be made clear. 

In discussing the use of mutants of microorganisms in the study of aromatic biosynthesis it was pointed out that valuable information could thus be obtained. An organism with a metabolic block rendering it unable to convert a substance X into its metabolite Y is likely either to excrete X, or to metabolize X by an alternative pathway if such is available, or to excrete metabolites of X formed by the action of relatively unspecific detoxicating systems. Accumulation or excretion of abnormal substances may therefore indicate an enzymic deficiency of this type. In the latter part of... 

S ATP + shikimate <3, 17, 19> (<3> SK2 is the isoenzyme that normally functions in aromatic biosynthesis in the cell, SKI functions only when high intracellular levels of shikimate occurs [3] <19> energy charge plays a role in regulating shikimate kinase, thereby controlling the shikimate pathway [10] <17> the enzyme catalyzes the committed step in the seven-step biosynthesis of chorismate [18]) (Reversibility <3, 17, 19> [3, 10, 18]) [3, 10, 18]... 

Catalyzed conversion of D-glucose into c/s, c/s-muconic acid (27) required creation of a biosynthetic pathway not known to exist naturally (Figure 5). This pathway relied on DHS dehydratase (Figure 5, enzyme A) (44,45) to couple aromatic biosynthesis to... 

Figure 8.4 Biosynthetic potentiai of Pseudomonas putida. Extended carbon core metabolism of Pseudomonas putida KT2440 including the major catabolic routes of Entner-Doudoroff pathway, Embden-Meyerhof-Parnas pathway, pentose phosphate pathway, tricarboxylic acid cycle, glyoxylate shunt, anaplerotic reactions, fatty acid de novo biosynthesis, p-oxidation of fatty acids, as well as the convergent -ketoadipate pathway for catabolism of aromatics. Known pathways for respective precursor supply for the broad product spectrum of P. putida KT2440 are indicated by light red arrows. Natural products and substrates are highlighted in black, heterologous products and substrates In red.

Solaiman DK, Ashby RD (2005) Rapid genetic characterization of poly(hydroxyalkanoate) synthase and its applications. Biomacromolecules 6 532-537 Song JJ, Yoon SC (1996) Biosynthesis of novel aromatic copolyesters from insoluble 11-phenoxyundecanoic acid by Pseudomonas putida BMOl. Appl Environ Microbiol 62 536-544 Steinbiichel A (2001) Perspectives for biotechnological production and utilisation of biopolymers metabohc engineering of poly-hydroxyalkanoate biosynthesis pathways as a successful example. Macromol Biosci 1 1-24... 

Aromatic biosynthesis, aromatizatioa biosynthesis of compounds containing the benzene ring system. The most important mechanisms are 1. the shi-kimate/chorismate pathway, in which the aromatic amino acids, L-phenylalanine, L-tyrosine and L-trypto-phan, 4-hydroxybenzoic acid (precursor of ubiquinone), 4-aminobenzoie acid (precursor of folic acid) and the phenylpropanes, including components of lignin, cinnamic acid derivatives and flavonoids are synthesized and 2. the polyketide pathway (see Polyke-tides) in which acetate molecules are condensed and aromatic compounds (e.g. 6-methylsalicylic acid) are synthesized via poly-fl-keto acids. Biosynthesis of flavonoids (e.g. anthocyanidins) can occur by either pathway. 

Biosynthesis. C. are products of the shikimic acid pathway of Aromatic biosynthesis (see). The key intermediate is trons-cinnamic acid, which may be converted either to coumarin itself, or become hydroxy-... 

Phenazines compounds based on the phenazine ring system (Table). All known naturally occurring P. are produced only by bacteria, which excrete them into the growth medium. Both six-membered carbon rings of P. are biosynthesized in the shikimate pathway of aromatic biosynthesis, via chorismic acid (not from anthranilate, as reported earlier). The earliest identified biosynthetic intermediate after chorismate is phenazine 1,6-dicarboxylate, which has been isolated from Pseudomonas phenazinium and from non-... 

Shikimate pathway of aromatic biosynthesis Naphthoquinones, anthraquinones, quinoline and quinazoline alkaloids, phena-zines. 

Figure 12.4 Simplified diagram of the general aromatic amino acid biosynthesis pathway. (Tryptophan biosynthesis proceeds from chorismate in five steps in all organisms. Phenylalanine is synthesized from arogenate or phenylpyruvate (Cyanobacteria, Saccharomyces cerevisiae, E. coli, C. glutamicum), whereas tyrosine is synthesized from arogenate or 4-hydroxy phenylpyruvate Saccharomyces cerevisiae, E. coli). In Pseudomonas aeuroginosa two alternative pathways coexist.)...

Bacteria, fungi, and plants share a common pathway for the biosynthesis of aromatic amino acids with shikimic acid as a common intermediate and therefore named after it—the shikimate pathway. Availability of shikimic acid has proven to provide growth requirements to tryptophan, tyrosine, and phenylalanine triple auxotrophic bacterial strains. Chorismate is also the last common precursor in the aromatic amino acid biosynthetic pathway, but the pathway is not named after it, as it failed to provide growth requirements to the triple auxotrophs. The aromatic biosynthetic pathway starts with two molecules of phosphoenol pyruvate and one molecule of erythrose 4-phosphate and reach the common precursor, chorismate through shikimate. From chorismate, the pathway branches to form phenylalanine and tyrosine in one and tryptophan in another. Tryptophan biosynthesis proceeds from chorismate in five steps in all organisms. Phenylalanine and tyrosine can be produced by either or both of the two biosynthetic routes. So phenylalanine can be synthesized from arogenate or phenylpyruvate whereas tyrosine can be synthesized from arogenate or 4-hydroxy phenylpyruvate. 

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