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James R Walker
Professor Emeritus
Molecular Biosciences-
Research Summary:
My research interests include the mechanism by which the bacterial chromosome is replicated, how replication is controlled, and how replication is integrated with cell division. Specifically, we study components of the Escherichia coli replicative polymerase, DNA polymerase III, the specific functions of some of the subunits of this ten-protein complex, and how the genes which encode these subunits are expressed and regulated. Also under study is the mechanism by which a critical activator protein initiates replication at the unique replication origin once and only once in each cell cycle and always at the same time in the cell cycle. E. coli was chosen as a model for replication in higher organisms because the mechanisms are thought to be very similar, but work with E coli provides the advantage of superior technology and genetic analysis.
We are interested also in the structure and developmental biology of long, ribbon-like appendages attached to Clostridium spores.
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Publications:
2007 Walker, J.R. A.J. Gnanam, A.L. Blinikova, M.J. hermandson, M.A. Karymov, Y.L. Lyubchenko, P.R. Graves, T.A. Haystead and K.D. Linse, Clostridium taeniosporum spore ribon-like appendage structure, composition and genes, Molecular Biology 63: 629-643
2006 Blinkova, A. L., A.J. Gnanam and J.R. Walker , Chromosomal DNA fragment encoding the clostridium taeniosporum endospore appendage component protein P25a and possibly related other proteins, GenBank Accession
2006 Gnanam, A.. J., A. Blinkova and J.R. Walker, Clostridium taeniosporum chromosomal fragment encoding endospore appendage components GP85 and P25b and possibly related proteins, GenBank Accession
2006 Walker JR, Severson KA, Hermandson MJ, Blinkova A, Carr KM, Kaguni JM, Escherichia coli DnaA protein: specific biochemical defects of mutant DnaAs reduce initiation frequency to suppress a temperature-sensitive dnaX mutation, Biochimie 88: 1-10
2003 Blinkova A, Hermandson MJ, Walker JR, Suppression of Temperature-Sensitive Chromosome Replication of an Escherichia coli dnaX(Ts) Mutant by Reduction of Initiation Efficiency, J. Bacteriol 185: 3583-3595
2001 Boye E, Blinkova A, Walker JR, Defective Initiation in an Escherichia coli dnaA(Cs,Sx) Mutant, Biochimie 83: 25-32
2000 Walker JR, Hervas C, Ross JD, Blinkova A, Walbridge MJ, Pumarega EJ, Park MO, Neely HR, Escherichia coli DNA polymerase III tau- and gamma-subunit conserved residues required for activity in vivo and in vitro, J Bacteriol 182: 6106-6113
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