Speaker: Dr B. Tracy Nixon, Professor - Biochemistry & Molecular Biology, Penn State
Title: The Importance of Spatial Organization: Structure / Function Studies of Bacterial Enhancer Binding Proteins and Cellulose Synthases
Abstract: Bacterial enhancer binding proteins regulate important adaptive responses in pathogens and other interesting bacteria, and cellulose synthases contribute to biofilms and plant cell walls. To control these microbial responses or to harvest cellulose as a renewal energy source we must understand the functioning of the molecular machines that drive transcription underpinning the adaptive behavior and spinning of the cellulose microfibrils that reinforce plant cell walls. A combination of molecular genetics, biophysics, bioinformatics and molecular dynamics reveal the importance of spatial organization of the subunits of both of these biomachines: homo-oligomers of AAA+ ATPases on the one hand, and cellulose synthases on the other. Together the information is beginning to reveal the functional basis of allosteric communication between nucleotide binding and target remodeling in bEBPs and cyclic di-GMP in bacterial cellulose synthases; on the horizon are similar studies of plant cellulose synthases. In particular mutant phenotypes, low and high resolution structures, solution scattering data, and molecular dynamic simulations of 1 microsec duration are teasing apart mechanisms of function in these two classes of molecular machines. I will present the highlights of our studies of the heptameric/hexameric Aquifex aelicous NtrC1 ATPase, the heterodimeric Rhodobacter sphaeroides BcsAB complex, and the 6x3 oligomer of plant CESA in Cellulose Synthase Complexes.