Profile of James M. Berger.

Whether he is restoring his 1976 Triumph TR6 British roadster or analyzing proteins, James Berger is curious about how machines work and what fuels them. Berger, a professor in the Department of Biophysics and Biophysical Chemistry at Johns Hopkins University School of Medicine, primarily studies biological nanomachines, which are fueled by the cellular energy currency ATP and carry out coordinated mechanical tasks. For more than two decades, his work on molecular machines has shed light on DNA replication and chromosome topology at the atomic level. Applying these endeavors to potential medical applications, Berger and his colleagues have described the function of enzymes underlying chemotherapy targets, research that could lead to more effective anticancer treatments. For example, Berger, a member of the National Academy of Sciences, has analyzed a class of antibiotics known as fluoroquinolones. His team has described the X-ray crystal structures of nine different fluoroquinolone–enzyme–DNA complexes for the Mycobacterium tuberculosis gyrase, a bacterial enzyme that relieves supercoiling in DNA. The findings help to explain the antibacterial resistance of the etiological agent for tuberculosis, a major public health threat. The findings also point to new approaches for overcoming the disease.