Part:BBa_J45999:Design
From partsregistry.org
E. coli strain YYC912; Odor-free chassis
- 10COMPATIBLE WITH RFC[10]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
Design Notes
A key challenge in our work to reprogram bacterial odor was to ensure that the natural, fecal odor of E. coli did not overpower our engineered wintergreen and banana odors. Indole was suggested to be the primary component of the fecal odor of E. coli (E Pichersky, personal communication, 2008). We confirmed that indole was the primary odor produced by E. coli by smelling LB Lennox medium supplemented with indole at a concentration comparable to that of LB cultures of E. coli strain MG1655 (~300 μM) [1]. In nature, E. coli uses indole for intercellular signaling in biofilm formation [2]. Since indole is not essential for cell viability, we could reprogram bacterial odor by modifying cellular metabolism for decreased indole production.
Indole is a product of the tryptophanase enzyme encoded by the tnaA gene of the tna operon in E. coli [3]. Mutations to the tna operon can reduce indole levels [4]. We tested four E. coli strains as potential odor-free chassis for our engineered system: YYC912, JC12337, MEB61, and MB408 (CGSC 7602, CGSC 6373, CGSC 6836, and CGSC 7152, respectively) [5, 6, 7]. The four strains all carry mutations in the tnaA gene. By smelling overnight liquid LB cultures of each strain, we selected E. coli strain YYC912 as an odor free chassis for our engineered system. We confirmed via gas chromatography analysis that E. coli strain YYC912 produced no measurable indole in comparison to E. coli strain TOP10.
Source
We thank Mary Berlyn for useful advice regarding tna operon mutants and The Coli Genetic Stock Center for E. coli strains YYC912 (CGSC 7602), JC123337 (CGSC 6373), MEB61 (CGSC 6836), and MB408 (CGSC 7152).
References
- Wang D, Ding X, and Rather PN. Indole can act as an extracellular signal in Escherichia coli. J Bacteriol 2001 Jul; 183(14) 4210-6. doi:10.1128/JB.183.14.4210-4216.2001 pmid:11418561.
- Snell EE. Tryptophanase: structure, catalytic activities, and mechanism of action. Adv Enzymol Relat Areas Mol Biol 1975; 42 287-333. pmid:236639.
- Rezwan F, Lan R, and Reeves PR. Molecular basis of the indole-negative reaction in Shigella strains: extensive damages to the tna operon by insertion sequences. J Bacteriol 2004 Nov; 186(21) 7460-5. doi:10.1128/JB.186.21.7460-7465.2004 pmid:15489459.
- Chang YY, Wang AY, and Cronan JE Jr. Expression of Escherichia coli pyruvate oxidase (PoxB) depends on the sigma factor encoded by the rpoS(katF) gene. Mol Microbiol 1994 Mar; 11(6) 1019-28. pmid:8022274.
- Ream LW, Margossian L, Clark AJ, Hansen FG, and von Meyenburg K. Genetic and physical mapping of recF in Escherichia coli K-12. Mol Gen Genet 1980; 180(1) 115-21. pmid:6255290.
- Edwards RM and Yudkin MD. Location of the gene for the low-affinity tryptophan-specific permease of Escherichia coli. Biochem J 1982 May 15; 204(2) 617-9. pmid:7052072.
- Martino PD, Fursy R, Bret L, Sundararaju B, and Phillips RS. Indole can act as an extracellular signal to regulate biofilm formation of Escherichia coli and other indole-producing bacteria. Can J Microbiol 2003 Jul; 49(7) 443-9. doi:10.1139/w03-056 pmid:14569285.
