Difference between revisions of "Part:BBa K567015"

Revision as of 03:02, 6 October 2011

PT7-metGN

T7 promoter-metG(truncated). This biobrick is constructed by putting the truncated metG (MetRS) under the control of T7 promoter and lac operator. We have cloned metG from E.coli and the tRNA recognition domain of MetRS is truncated. KanaR gene with start codon substituted for CGA is used to testify the function of mutated metG. When this biobrick and metY-CGA (BBa_K567016) are co-transformed into the cell, the cells can survive on the LB Kana plate.

Construction of BBa_K567015

Rational design of MetRS: we have obtained a truncated MetRS without anticodon recognition domain. The structure of the truncated protein is shown below. This modified MetRS can charge tRNA^Met without recognizing its anticodon.

Fig. This design is based on the crystal structure of methionyl-tRNA synthetase complex with tRNA (PDB ID：2CSX). We have superimposed the crystal structure of methionyl-tRNA synthetase from E.coli and obtained the overlay structure after kinetics optimization. Above is the picture showing E.coli methionyl-tRNA synthetase with (left) and without (right) anticodon recognition domain. The picture proposed that E.coli methionyl-tRNA synthetase will lose the ability to bind tRNA^Met anticodon if anticodon recognition domain is deleted, thus losing anticodon specificity while maintaining aminoacylation ability. We have built the truncated MetRS, PT7-metGN (BBa_K567015), based on this design.

Characterization of BBa_K567015

When this part, metY-CGA (BBa_K567016) and KanaR (BBa_K567020) are co-transformed into the cell, the cell is expected to survive Kana. We tested the activity of the truncated MetRS PT7-metGN (BBa_K567015)and found that the truncated MetRS acted as expected, losing specificity for tRNA^Met anticodon while maintaining aminoacylation ability.

Fig. Growth of ER2566 with a. metGN + metY-CGA, b. metGM + metY-CGA, c. + metGN, d. + metGM. Growth medium (left): LB Kana+Tet. Growth medium (right): LB Kana.

Cell growth shows that the cells show Kana resistance only when both modified MetRS (metGN) and modified tRNA^Met(metY-CGA) are transformed into the cell, proving that tRNA metY-CGA can transfer fMet to CGA when it is used as the start codon

For more information concerning this part, please see [http://2011.igem.org/Team:SJTU-BioX-Shanghai 2011 SJTU-BioX-iGEM]

Related Biobrick:

PT7-metGM (BBa_K567014)

metY-CGA (BBa_K567016)

Sequence and Features