Subsystem: Cinnamic Acid Degradation
This subsystem's description is:
In Escherichia coli Hca and Mhp enzymes catalyze the degradation of the aromatic compounds 3-phenylpropionate (PP) and cinnamic acid (CI) and allow the use of PP as sole carbon source.
Hca cluster encoding the dioxygenolytic pathway for initial catabolism of 3-phenylpropionic acid (PP) in Escherichia coli K-12 is composed of five catabolic genes arranged as a putative operon (hcaA1A2CBD) and two additional genes transcribed in the opposite direction that encode a potential permease (hcaT) and a regulator (hcaR). Sequence comparisons revealed that while hcaA1A2CD genes encode the four subunits of the 3-phenylpropionate dioxygenase, the hcaB gene codes for the corresponding cis-dihydrodiol dehydrogenase. The inducible expression of the hca genes requires the presence of the hcaR gene product, which acts as a transcriptional activator and shows significant sequence similarity to members of the LysR family of regulators.
Interestingly, the HcaA1A2CD and HcaB enzymes are able to oxidize not only PP to 3-(2,3-dihydroxyphenyl)propionate (DHPP) but also cinnamic acid (CI) to its corresponding 2,3-dihydroxy derivative. Further catabolism of DHPP requires the mhp-encoded meta fission pathway for the mineralization of 3-hydroxyphenylpropionate (3HPP). Expression in Salmonella typhimurium of the mhp genes alone or in combination with the hca cluster allowed the growth of the recombinant bacteria in 3-hydroxycinnamic acid (3HCI) and CA, respectively.
(CI) degradation = hcaA1A2CBD + hcaR + hcaT + mhpABCDEF
=========Variant codes:==============
1.0 - cinnamic acid (CI) degradation pathway is present;
2.0 - just 3-phenylpropionate degradation pathway, no CI catabolism genes
For more information, please check out the description and the additional notes tabs, below
| Literature References | Characterization of the hca cluster encoding the dioxygenolytic pathway for initial catabolism of 3-phenylpropionic acid in Escherichia coli K-12. DÃaz E Journal of bacteriology 1998 Jun | 9603882 | Cinnamic acid, an autoinducer of its own biosynthesis, is processed via Hca enzymes in Photorhabdus luminescens. Chalabaev S Applied and environmental microbiology 2008 Mar | 18245247 |
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| Diagram | Functional Roles | Subsystem Spreadsheet | Description | Additional Notes | |||||||||
In Escherichia coli Hca and Mhp enzymes catalyze the degradation of the aromatic compounds 3-phenylpropionate (PP) and cinnamic acid (CI) and allow the use of PP as sole carbon source. Hca cluster encoding the dioxygenolytic pathway for initial catabolism of 3-phenylpropionic acid (PP) in Escherichia coli K-12 is composed of five catabolic genes arranged as a putative operon (hcaA1A2CBD) and two additional genes transcribed in the opposite direction that encode a potential permease (hcaT) and a regulator (hcaR). Sequence comparisons revealed that while hcaA1A2CD genes encode the four subunits of the 3-phenylpropionate dioxygenase, the hcaB gene codes for the corresponding cis-dihydrodiol dehydrogenase. The inducible expression of the hca genes requires the presence of the hcaR gene product, which acts as a transcriptional activator and shows significant sequence similarity to members of the LysR family of regulators. Interestingly, the HcaA1A2CD and HcaB enzymes are able to oxidize not only PP to 3-(2,3-dihydroxyphenyl)propionate (DHPP) but also cinnamic acid (CI) to its corresponding 2,3-dihydroxy derivative. Further catabolism of DHPP requires the mhp-encoded meta fission pathway for the mineralization of 3-hydroxyphenylpropionate (3HPP). Expression in Salmonella typhimurium of the mhp genes alone or in combination with the hca cluster allowed the growth of the recombinant bacteria in 3-hydroxycinnamic acid (3HCI) and CA, respectively. (CI) degradation = hcaA1A2CBD + hcaR + hcaT + mhpABCDEF =========Variant codes:============== 1.0 - cinnamic acid (CI) degradation pathway is present; 2.0 - just 3-phenylpropionate degradation pathway, no CI catabolism genes ============REFERENCES:==================== 1. Chalabaev S, Turlin E, Bay S, Ganneau C, Brito-Fravallo E, Charles JF, Danchin A, Biville F. Cinnamic acid, an autoinducer of its own biosynthesis, is processed via Hca enzymes in Photorhabdus luminescens. Appl Environ Microbiol. 2008 Mar;74(6):1717-25. PMID: 18245247. 2. Díaz E, Ferrández A, García JL. Characterization of the hca cluster encoding the dioxygenolytic pathway for initial catabolism of 3-phenylpropionic acid in Escherichia coli K-12. J Bacteriol. 1998 Jun;180(11):2915-23. PMID: 9603882. 3. Torres, B., Porras, G., Garcia, J. L., Diaz, E. (2003). Regulation of the mhp Cluster Responsible for 3-(3-Hydroxyphenyl)propionic Acid Degradation in Escherichia coli. J. Biol. Chem. 278: 27575-27585 | |||||||||||||
