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 ReferencesCharacterization of the hca cluster encoding the dioxygenolytic pathway for initial catabolism of 3-phenylpropionic acid in Escherichia coli K-12. Díaz E Journal of bacteriology 1998 Jun9603882
Cinnamic acid, an autoinducer of its own biosynthesis, is processed via Hca enzymes in Photorhabdus luminescens. Chalabaev S Applied and environmental microbiology 2008 Mar18245247
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HcaBMhpBMhpCMhpDMhpAHcaCHcaDHcaA1HcaA2MhpEMhpT*MhpFHcaRMhpRHcaT
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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