Improvement of Bacterial
Two Hybrid System
LIAO
Gong-Xian, YU Guan-Qiao, ZHU Jia-Bi**
( Laboratory of Molecular Genetics, Shanghai Institute of Plant Physiology,
Shanghai Institute for Biological Sciences, the Chinese Academy of Sciences,
Shanghai 200032, China )
Abstract Bacterial
two-hybrid system is a newly developed method for studying protein protein
interactions, especially for effects of the environmental factors on the
interaction. In our studies of the effect of NH4＋ or oxygen on the NifL-NifA
interaction, it was found that E.coli strain DHP1 cya–,
when transformed by T18-NifL together with T25-NifA, exhibited high activity of
β-galactosidase in the presence of NH4＋, and appeared as red colonies
when grown in MacConkey/maltose agar. This indicated the direct interaction of
NifL and NifA. However,similar phenomena were also shown in the case of the
DHP1 cya– strain harboring T18-NifL or T25-NifL alone,
respectively, without its interacting counterpart T25-NifA or T18-NifA. In this
paper, a brief method is presented to detect the protein-protein interaction
using direct assay of the adenylate cyclase, thus minimizing the false
positives produced by the β-galactosidase activity assay or MacConkey/maltose
agar plating.
Key words bacterial two-hybrid system； false positives； NifL-NifA interaction
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