Currently we are screening the proteome of Treponema pallidum for protein-protein interactions. T. pallidum is the causative agent of syphilis but most Treponema proteins have homologs in other species.
Goal: The main purpose of the screening project is to find out the function of the many uncharacterized proteins in Treponema and related bacteria. Proteins of unknown function often interact with well characterized proteins (or vice versa), thus suggesting a function. The Treponema project will be finished this summer.
Collaborations: We can screen your homolog of interest or send you interaction data of Treponema homologs.
Other bacteria: Later this year we will start to work on the interaction maps of other bacteria. We are open to suggestions and will be happy to collaborate on the species of your interest.
Example: The interaction screen for Treponema flagellin (the main component of bacterial flagella):
(click image for larger [1.3 MB] version).
This screen resulted in a surprisingly large number of interactions (usually we find 1-4 hits). In addition, most interactions involved proteins of unknown function. However, only a subset of those were conserved proteins and only one, TP0658 (plate 7 in the image) turned out to be conserved widely in bacteria. We have shown in the meantime that TP0658 is indeed a conserved flagellar assembly factor (Titz et al., submitted).
Note also that flagellin interacts with itself (i.e. FlaB3, plate 11) and with another flagellar protein (FlgB, plate 4). It remains to be determined whether the interactions with GyrA and SpsF (plates 1 and 3) have any biological significance.
The screening procedure: Acreens are done in an automated fashion by testing all Treponema proteins agains a protein of interest. All screens are done in quadruplicate (as shown above) or in duplicate to ensure reproducibility of the interaction data. False positives can be largely avoided this way. More technical information is available.
Acknowledgments: This project is a collaboration between our lab and the group of Tim Palzkill, Baylor College of Medicine, Houston, USA.