Team:Evry/auxin production


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Auxin production


    The 2011 Imperial College iGEM ( project showed that the plant hormone auxin or indole-3-acetic acid (IAA) can be synthetized in E.coli through a two-step pathway from tryptophan. In their work, the genes encoding the auxin biosynthesis pathway originally coming from Pseudomonas savastanoi were expressed in Escherichia coli. In our project we aim to express this auxin biosynthesis pathway in Xenopus tropicalis . First, we plan to reengineer the auxin biosynthesis pathway in the tadpole with a ubiquitous and constitutive promoter. Once the system is functional, we intend to put the system under the control of tissue-specific promoters.

    By modelling the auxin biosynthesis pathway, we will be able to determine the number of auxin molecules produced per plasmids injected in the cell.


    Model description

    The plasmids containing the two genes involved in the auxin biosynthesis pathway, namely IaaM and IaaH, will be expressed in a ubiquitous and constitutive manner in a first step and in a second step in a tissue-specific manner. The IaaM gene encodes tryptophan-2-monooxygenase (IAAM) that catalyses the conversion of tryptophan (Trp) into indole-3-acetamide (IAM). The IaaH gene encodes indoleacetamide hydrolase (IAAH) that hydrolyse IAM to realease indole-3-acetic acid (IAA) [1]. At the same time, the synthesized IAM and IAA will competitively inhibit the enzyme activity of IAAM.

    All the reactions involved in the auxin biosynthesis pathway are illustrated in Figure 1.

    Figure 1. Auxin synthesis pathway (Diagram by 2012 Évry iGEM team)




    Limit conditions