Abstract:
FrzCD is a Methyl-accepting chemotaxis protein (MCP) of Myxococcus xanthus. It was
recently found to colocalize with the nucleoid and aid in the cooperative response of
bacteria to signals. Invitro DNA binding studies suggested the sequence-independent DNA
binding is by utilizing the N-terminal basic tail. MCPs have a sensor domain which is
generally periplasmic for ligand binding, a HAMP linker to amplify and transmit the signal
and a signaling unit to signal the downstream pathways. Our bioinformatic analysis has
found out the presence of two contiguous HAMP domains in FrzCD. We aim to investigate
the role of HAMP domains by systematic designing of domain deletion constructs and
performing protein oligomerization and DNA-binding studies. Our preliminary results
indicate that the higher order oligomerization of protein is mediated by the coiled-coil
signaling unit. In the DNA-free state, HAMP domains restrict oligomeric state of the protein
to a dimer. EMSA shows that coiled-coil domain stabilizes the protein-DNA complex
possibly through a higher-order array formation. We are progressing further to quantify the
binding affinities, to find the oligomeric state of the protein in the DNA-bound form and to
obtain the crystal structure of the protein.
