Part:BBa_K4083006

rhlB with SacI and SalI sites

The rhlB gene is responsible for the production of rhamnosyltransferase called RhlB in Pseudomonas aeruginosa.

Usage and Biology

P. aeruginosa is a gram-negative bacillus and opportunistic pathogen. It secretes rhamnolipids - the rhamnose containing glycolipid biosurfactant. These biosurfactants are used by P. aeruginosa to emulsify the oil substances for easy digestion. Thus, rhamnolipids can increase the availability of fats which can be important in many different areas like petroleum, bioremediation, cosmetics, food, agriculture, etc. [1] However, due to the toxicity and infectiousness of P. aeruginosa, other alternative organisms are tested. Currently, genetically engineered Pseudomonas putida has more promising results than others. P. putida only lacks two enzymes for mono-rhamnolipid production: RhlA and RhlB. These enzymes are encoded by rhlA and rhlB coding regions in rhlAB operon. It was previously thought that rhlA and rhlB forms heterodimer, however, further research showed that they act independently from each other [2].

Our team planned to extract rhLA and rhlB genes from P.aeruginosa and to insert them into pRGPDuo2 plasmid obtained from Gauttam, R. [3] We developed the new approach to increase the P. putida's rhamnolipid synthesis by adding nadE gene which encodes NAD synthetase. This way, we hoped to see more rhamnolipid production in engineered P. putida.

The rhamnosyltransferase B (RhlB) catalyzes the reaction between 3-(3-hydroxyalkanoyloxy)alkanoic acid and dTDP-L-rhamnose which forms mono-rhamnolipid [1].

Figure 1. RhlA and RhlB metabolic pathway

Reference

[1] Chong, H., & Li, Q. (2017, August 5). Microbial production of rhamnolipids: opportunities, challenges and strategies. Microbial Cell Factories. https://microbialcellfactories.biomedcentral.com/articles/10.1186/s12934-017-0753-2

[2] Wittgens, A., Kovacic, F., Müller, M. M., Gerlitzki, M., Santiago-Schübel, B., Hofmann, D., Tiso, T., Blank, L. M., Henkel, M., Hausmann, R., Syldatk, C., Wilhelm, S., & Rosenau, F. (2016). Novel insights into biosynthesis and uptake of rhamnolipids and their precursors. Applied Microbiology and Biotechnology, 101(7), 2865–2878. https://doi.org/10.1007/s00253-016-8041-3

[3] Gauttam, R., Mukhopadhyay, A., & Singer, S. W. (2020). Construction of a novel dual-inducible duet-expression system for gene (over)expression in Pseudomonas putida. Plasmid, 110. https://doi.org/10.1016/j.plasmid.2020.102514

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal XhoI site found at 1172
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal NgoMIV site found at 65
  Illegal NgoMIV site found at 786
  Illegal NgoMIV site found at 899
  
• 1000
  COMPATIBLE WITH RFC[1000]