SPINE

=SPINE is a method to detect in vivo protein-protein interactions= PubMed

A detailed protocol to detect the interaction between RocG and GltC:

1 litre of a Bacillus subtilis culture was grown to an OD600 of approx. 1.0 and incubated with 0.6% formaldehyde (stock solution 4% in PBS, pH 6.5!) for 20 minutes @ 37°C on a shaker. The cells were harvested and washed once in 1 X PBS pH 6.5. The pellets can then be stored @ -20 °C. The GltC protein was expressed carrying a Strep-tag and RocG expression was induced by arginine (PubMed). Expression of the Strep-tagged GltC protein allows to test the functionality of the protein. Crude extracts (10-15 ml) were prepared by using a French Press. After a centrifugation step for 1 h @ 27.000 g the clarified crude extracts were loaded onto a Streptactin sepharose column (0.5-1 ml matrix) to isolate the cross-linked protein complexes (the detailed procedure for protein purification is described in the IBA manual, http://www.iba-go.com/). After the purification of the protein complexes the crosslinks can be resolved by boiling the samples in laemmli buffer for 10-15 minutes @ 95 °C (PubMed). A 12.5% SDS gel was loaded with the samples and the proteins were then visualized by silver-staining. We identified the interaction partner/s by mass spectroscopy and Western blotting.

Preparation of the formaldehyde stock solution (max. 4% in 1X PBS pH 6.5): We use paraformaldehyde (a white powder). Paraformaldehyde can be solved in 1 X PBS for approx. 20-30 minutes @ 65 to 70 °C.

The sepharose matrix was purchased from the IBA company, Göttingen (http://www.iba-go.com/).

Relevant plasmids:

for use in B. subtilis: pGP380, pGP382

for use in E. coli: pGP172, pGP574

The reference for the method:

Herzberg, C., Flórez Weidinger, L. A., Dörrbecker, B., Hübner, S., Stülke, J. & Commichau, F. M. (2007) SPINE: A method for the rapid detection and analysis of protein-protein interactions in vivo. Proteomics 7: 4032-4035. PubMed

Other studies that made use of SPINE

1. Commichau, F. M., Herzberg, C., Tripal, P., Valerius, O., and Stülke, J. (2007) A regulatory protein-protein interaction governs glutamate biosynthesis in Bacillus subtilis: The glutamate dehydrogenase RocG moonlights in controlling the transcription factor GltC. Mol Microbiol 65: 642-654. PubMed
2. Commichau, F. M., Rothe, F. M., Herzberg, C., Wagner, E., Hellwig, D., Lehnik-Habrink, M., Hammer, E., Völker, U. & Stülke, J. (2009) Novel activities of glycolytic enzymes in Bacillus subtilis: Interactions with essential proteins involved in mRNA processing. Mol. Cell. Proteomics in press PubMed