Matsumura Home Page

Welcome to the Homepage for Dr. Philip Matsumura's lab. Our lab has been studying signal transduction in bacterial chemotaxis. The Escherichia coli flagellar/chemotaxis system is an extraordinarily well studied system with virtually all of its components characterized on genetic, biochemical and molecular levels. Bacterial chemotaxis is also an example of a conserved signalling system in all prokaryotes and some eucaryotes called "two-component" regulatory systems. Understanding the mechanism of chemotaxis provides a framework to understand diverse sensory phenomena in bacteria such as, sporulation in Bacillus, plant tumor formation in Agrobacterium, or osmoregulation in E. coli.


email us - Philip.Matsumura@uic.edu

During the last 15 years, we have cloned, sequenced, overproduced and purified a number of the soluble components of this signalling system. Using these purified proteins and antibodies against these proteins, we have isolated complexes of these proteins from cells. Further, some complexes can be formed in vitro. The complexes have altered biochemical properties which more accurately reflect the in vivo signalling process and are likely to reflect the in situ state of these proteins.

By using a combination of genetics and structural chemistry, we have, in collaboration with Dr. Karl Volz, mapped the interacting surface of one of the chemotaxis proteins, CheY, with its target on the flagellar motor, FliG. The positions of dominant suppressing mutations which compensate for defects in FliG have been shown to cluster in three dimensions on the high resolution crystal structure of CheY. The clustering of these mutations supports the genetic prediction that dominant, allele-specific suppression identifies regions of physical interaction between gene products.

In collaboration with Dr. Frederick Dahlquist at University of Oregon, we have used multidimensional NMR to identify residues which undergo large chemical shift changes during phosphorylation. These results indicate that regions which change upon phosphorylation overlap the signalling surface identified by the genetic suppression analysis.

Finally, we have studied the regulation of groups of operons which code for the flagellar and chemotaxis proteins. These gene products are coordinately expressed in a cascade of regulation. We have characterized the master regulatory operon which is required for all subsequent gene expression. The FlhD and FlhC proteins have been overexpressed, purified and have been shown to be active in a complex of 2 D: 2C. This heteromeric complex has been footprinted to the -40 to -80 region in a number of level II flagellar operons and requires sigma-70 for transcriptional activity. In addition, we have shown that FlhD, but not FlhC, is a regulator of other nonflagellar operons. Recently, we have shown that FlhD affects cell division as well as flagellar operons. Although this is not uncommon in eucaryotic regulators such as c-fos and c-jun, it maybe the first example of transcription factor combinatorial specificity in prokaryotes. That is, the altering of DNA binding specificity by complex formation.

publication list Includes publications from the Matsumura lab for the past 10 years
current lab members List of current lab members and their CVs, publication abstracts, and research project summaries.
List of Graduate Students and Postdoctoral Fellows who were members of the Matsumura lab.

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