Quinaldine Pathway Map

Quinaldine (2-methylquinoline) is a derivative of the heterocyclic compound quinoline. It can be extracted from coal tar, prepared from aniline and paraldehyde (Skraup synthesis), or from aniline and crotonaldehyde (Doebner-von Miller Variation of the Skraup synthesis). It is harmful if swallowed or absorbed through the skin and may cause burns when in contact with skin or eyes.

Quinaldine can be utilized by Arthrobacter nitroguajacolicus Ru61a (formerly Arthrobacter ilicis) as a sole source of carbon and energy (Katja Parschat et al., 2007). The upper pathway involves the conversion of quinaldine to anthranilate via a gene cluster encoding quinaldine 4-oxidase (Qox) (Parschat et al., 2003), 1H-4-oxoquinaldine 3-monooxygenase (Moq), a 2,4-dioxygenase (Hod) catalyzing heterocyclic ring cleavage of 1H-3-hydroxy-4-oxoquinaldine to carbon monoxide and N-acetylanthranilate (Frerichs-Deeken et al., 2005), and an aryl-acylamidase that forms anthranilate and acetate. The lower pathway involves the mineralization of anthranilate via catechol formation and ortho ring cleavage.

The conjugative linear plasmid pAL1 in A. nitroguajacolicus Ru61a was found to contain the gene cluster responsible for the conversion of quinaldine to anthranilate (Overhage et al., 2005). It has also been reported in many Streptomyces spp., several Rhodococci and Mycobacteria, Planobispora rosea, the plant pathogen Clavibacter michiganensis, and a Terrabacter sp.

The following is a text-format quinaldine 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 (8k) format.

                            Quinaldine 
                Arthrobacter nitroguajacolicus Ru61a
                            and others               
                                |
                                |
                                | quinaldine
                                | 4-oxidase
                                | 
                                v                               
                       1H-4-Oxoquinaldine      
                                |
                                |
                                | 1H-4-oxoquinaldine 
                                | 3-monooxygenase
                                | 
                                v  
	            2-Methylquinoline-3,4-diol
                                |
                                |
                                | 1H-3-hydroxy-4-oxoquinaldine
                                | 2,4-dioxygenase 
                                | 
                                v  
	              N-Acetylanthranilate 
                                |
                                |
                                | N-acetylanthranilate 
                                | amidase
                                | 
                                v
                         2-Aminobenzoate 
                                |
                                |
                                |
                                v
                              to the
                         2-Aminobenzoate
                             pathway

Page Author(s): Wanying Yao

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