Difference between revisions of "Part:BBa K2718006"

Revision as of 21:36, 16 October 2018

PLac Promoter-Methionine-y-Lyase-HisTag

The Plac promoter (BBa_R0011) is a hybrid regulatory region consisting of the promoter P(L) of phage lambda with the cI binding sites replaced with lacO1. The hybrid design allows for a strong promoter that can nevertheless be:

• repressed by LacI, the Lac inhibitor (i.e. repressor).
• induced by [http://openwetware.org/wiki/IPTG IPTG] in E.Coli DH5-alpha.

This promoter (BBa_R0011) is assembled with Methionine-y-lyase-Histag (BBa_K2718005) to produce the methionine-y-lyase-histag.

Protein production

Different growing conditions were tested to determine the best growing conditions. The production was also tested two types E.coli bacteria :

• DH5a
• BL21 DE3

To verify the production of methionine-y-lyase, an SDS PAGE was performed and stained with Coomassie blue using cells containing this Biobrick and a Western Blot was performed with anti-his tag antibodies, revealed with alkaline phosphatase.

Purification of the protein

The histidine tag present in c-terminal of the protein allows us to purify the protein on a nickel NTA column. In our case, the protein was purified using an "Akta pure" on Histrap column (GE Healthcare).

Fig 5. SDS PAGE after purification, NR = non-restraint, 1, 8 and 10-15 correspond to the eluted fractions

Protein activity

To characterize methionine-γ-lyase, activity tests were done :

• DTNB (5,5′-Dithiobis 2-nitrobenzoic acid) test : DTNB reacts with thiol group so for methionine-y-lyase, DTNB reacts with thiol group of methanethiol
• MTBH (3-Methyl-2-benzothiazolinone hydrazone hydrochloride hydrate) test : MBTH reacts with alpha-keto compounds so for methionine-y-lyase, MTBH reacts with 2 oxobutanoate.

alt text

Figure 6 : Scheme of the reaction of the methionin-y-lyase activity test

Sequence and Features