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Biochemistry, Biophysics, and Structural Biology Commons

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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Protein-Protein And Protein-Dna Interactions At The Bacteriophage T4 Dna Replication Fork. Characterization Of A Fluorescently Labeled Dna Polymerase Sliding Clamp, Daniel J. Sexton, Theodore E. Carver, Anthony J. Berdis, Stephen J. Benkovic Nov 1996

Protein-Protein And Protein-Dna Interactions At The Bacteriophage T4 Dna Replication Fork. Characterization Of A Fluorescently Labeled Dna Polymerase Sliding Clamp, Daniel J. Sexton, Theodore E. Carver, Anthony J. Berdis, Stephen J. Benkovic

Chemistry Faculty Publications

The T4 DNA polymerase holoenzyme is composed of the polymerase enzyme complexed to the sliding clamp (the 45 protein), which is loaded onto DNA by an ATP-dependent clamp loader (the 44/62 complex). This paper describes a new method to directly investigate the mechanism of holoenzyme assembly using a fluorescently labeled cysteine mutant of the 45 protein. This protein possessed unaltered function yet produced substantial changes in probe fluorescence intensity upon interacting with other components of the holoenzyme. These fluorescence changes provide insight into the role of ATP hydrolysis in holoenzyme assembly. Using either ATP or the non-hydrolyzable ATP analog ...


The Carboxyl Terminus Of The Bacteriophage T4 Dna Polymerase Is Required For Holoenzyme Complex Formation, Anthony J. Berdis, Patrice Soumillion, Stephen J. Benkovic Nov 1996

The Carboxyl Terminus Of The Bacteriophage T4 Dna Polymerase Is Required For Holoenzyme Complex Formation, Anthony J. Berdis, Patrice Soumillion, Stephen J. Benkovic

Chemistry Faculty Publications

To further elucidate the mechanism and dynamics of bacteriophage T4 holoenzyme formation, a mutant polymerase in which the last six carboxyl-terminal amino acids are deleted, was constructed, overexpressed, and purified to homogeneity. The mutant polymerase, designated ΔC6 exo−, is identical to wild-type exo− polymerase with respect to kcat, kpol, and dissociation constants for nucleotide and DNA substrate. However, unlike wild-type exo− polymerase, the ΔC6 exo− polymerase is unable to interact with the 45 protein to form the stable holoenzyme. A synthetic polypeptide corresponding to the carboxyl terminus of the wild-type exo− polymerase was tested as an in vitro inhibitor of ...


The Lipooligosaccharides Of Haemophilus Ducreyi Are Highly Sialylated, William Melaugh, A A. Campagnari, B W. Gibson Jan 1996

The Lipooligosaccharides Of Haemophilus Ducreyi Are Highly Sialylated, William Melaugh, A A. Campagnari, B W. Gibson

Chemistry Faculty Publications

The major lipooligosaccharides of the sexually transmitted pathogen Haemophilus ducreyi 35000 have been previously found to terminate in N-acetyllactosamine and sialyl-N-acetyllactosamine, Neu5Ac alpha 2-->3Gal beta 1-->4GlcNAc (W. Melaugh, N. J. Phillips, A. A. Campagnari, M. V. Tullius, and B. W. Gibson, Biochemistry 33: 13070-13078, 1994). In this study, mass spectrometry and composition analyses have shown that the lipooligosaccharides from three other H. ducreyi strains also contain N-acetyllactosamine and are highly sialylated (approximately 30 to 50%), although one African strain was found to contain neither of these structural features.