Syringate Pathway Map

Syringate and gallate are intermediate metabolites of lignin and product of microbial metabolism of anthocyanins and other polyphenols. Lignin is an important part in the terrestrial carbon cycle and is the most abundant of all the aromatic compounds. Lignin is found in the secondary structure of the cell walls of plants, trees and other vegetation (Martone et al., 2009). Its main function is to provide support to the cell walls by integrating into the spaces of the cell walls. Microbial degradation of lignin helps in the conversion of lignin into useful chemical products which are free from toxins.

The degradation of Syringate and Gallate lead to the production of pyruvate and oxaloacetate, both of which are critical components involved in multiple pathways, including the Krebs Cycle, amino acid catabolism, fermentation and gluconeogenesis (Kasai et al., 2005). This page shows only aerobic pathway of gallate. The anaerobic degradation of gallate is documented elsewhere in EAWAG-BBD.

The following is a text-format Syringate pathway map. An organism which can initiate the pathway is given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (12k) format.

                                           Syringate
                                   Sphingomonas paucimobilis
                                             SYK-6
                                               |
                                               | tetrahydrofolate-
                                               | dependent O-demethylase
                                               |
                                               v                                                           from the
                                    3-O-Methylgallate (3MGA)                                               Vanillin
                                               |                                                            Pathway
                                               |                                                               |
                                               |                                                               |
                    +--------------------------+---------------------------+                                   |
                    |                          |                           |                                   v
                    | 3MGA                     | 3MGA                      | PCA                  2-Hydroxy-4-carboxymuconate
                    | O-demethylase            | 3,4-dioxygenase           | 4,5-dioxygenase              semialdehyde
                    |                          |                           |                                   |
                    v                          v                           v                                   |
                 Gallate             4-Carboxy-2-hydroxy-     A      2-Pyrone-4,6-                             |
                    |                6-methoxy-6-Oxohexa- --------> dicarboxylate (PDC) <----------------------+
                    |                2,4-dienoate (CHMOD)                  |             2-Hydroxy-4-carboxymuconate
                    |                          |                           |             semialdehyde dehydrogenase
                    | gallate                  | CHMOD                     | PDC
                    | dioxygenase              | hydrolase                 | hydrolase
                    |                          |                           |
                    +--------------------------+---------------------------+
                                               |
                                               |
                                               |
                                               v
                                       4-Oxalomesaconate
                                               |
                                               |
                                               |
                                               |
                                               v
                                         Intermediary
                                          Metabolism
                                            (KEGG)

Page Author(s): Jeanna Danielson, Sujana Mittapalli

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http://eawag-bbd.ethz.ch/syr/syr_map.html