Yeast bacterial two-hybrid system and methods of use thereof

1. An isolated nucleic acid comprising a promoter sequence of SEQ ID NO: 1 which drives expression of an operably linked coding sequence in both yeast and bacteria.

2. A plasmid comprising the promoter of claim 1 selected from the group consisting of SEQ ID NO: 2 (pGLS20), SEQ ID NO: 3 (pGLS22) and SEQ ID NO: 4 (pGLS23).

3. A yeast or bacterial host cell expressing a plasmid of claim 2 .

4. The host cell of claim 3 selected from the group consisting of S. cerevisiae SKY191, PRT50, diploid strain SKY191 and PRT50.

5. The host cell of claim 3 which is E. coli KJ1567 or E. coli AG58A(RP28).

6. A method for comparing binding interactions between a first protein and a second protein in both bacterial and yeast organismal milieus using a construct which functions in both organisms, comprising

a) providing a yeast host cell and a bacterial host cell, each cell comprising,

i) a reporter gene operably linked to a DNA sequence comprising a protein binding site;

ii) a first fusion gene which expresses a first fusion protein, said first fusion protein comprising said first protein covalently bonding to a binding moiety which is capable of specifically binding to said protein binding site which is driven by the promoter sequence as claimed in claim 1 and

iii) a second fusion gene which expresses a second fusion protein, said second fusion protein comprising said second protein covalently bonded to a gene activating moiety;

b) allowing said first and second proteins to interact; and

c) measuring expression of said reporter gene as a measure of said interaction between said first and second proteins in both bacteria and yeast.

7. A unified yeast and bacterial two-hybrid system for practicing the method of claim 6 , comprising:

a) a plasmid selected from the group consisting of SEQ ID NO: 2 (pGLS20), SEQ ID NO: 3 (pGLS22) and SEQ ID NO: 4 (pGLS23);

b) at least one of pAC-AMP-αLPL and pBR-AMP-αLPL (SEQ ID NO: 5);

c) an E. coli strain selected from the group consisting of E.coli KJ1567 and E. coli AG58A(RP28); and

d) a yeast strain selected from the group consisting of PRT50, SKY191 and PRT475.