Two-dimensional concentration of receptor fragments modulates signaling activity in a surface-templated system
Abstract (Summary)Transmembrane signaling events in both eukaryotic and prokaryotic cells occur in the two-dimensional space defined by the lipid membrane. Cellular responses are regulated through processes that involve the recruitment of specific signaling proteins to the membrane surface. These phenomena suggest the importance of clustering and 2D concentration of membrane-bound receptor complexes in signaling. Previously a template-directed method was used to assemble and restore biochemical activity to the cytoplasmic signaling proteins of the E. coli chemotaxis system using a histidine-tagged cytoplasmic fragment of the aspartate receptor (CF) and Ni-NTA lipid vesicles (Shrout et al. 2003). Here, we employed this approach to vary the 2D concentration of CF, which is influenced both CheA activation and methylation. Our data showed that rates of templated CF methylation and the activity of CheA complexes both increased substantially when the 2D concentration of CF was increased. The differing influences of CF density on CheA activation and CF methylation provide a means to regulate CheA activity through receptor clustering.
School Location:USA - Massachusetts
Source Type:Master's Thesis
Date of Publication:01/01/2006