JOIN US IN CELEBRATING A Century of Saving Lives
1916 ‐ 2016
Department of Biochemistry and Molecular Biology Centennial Kick-Off Lecture
February 29, 2016
The Department officially began its Centennial celebrations with a lecture given by Dr. Roger McMacken and entitled “Reflections on the history and impact of biochemistry and molecular biology in the Bloomberg School of Public Health during the “DNA Era”.
In celebration of the Johns Hopkins Bloomberg School of Public Health’s 100th year, the Department of Biochemistry & Molecular Biology will present a special historical perspective seminar to be given by Dr. Roger McMacken. A faculty member of the School of Public Health for 40 years, Dr. McMacken was recruited to Johns Hopkins University in 1976 by Dr. Lawrence Grossman, the 3rd Chair of the Department of Biochemistry. After establishing a successful research laboratory and promotion to Professor, Dr. McMacken was appointed as the 4th Chair of the Department in 1990, and served in this leadership role until 2008. During his tenure as Chair, Dr. McMacken diversified the department’s interests through the hiring of new faculty and guided the integration of the department with both the Division of Biophysics and the Division of Reproductive Biology.
Professor McMacken’s laboratory utilizes biochemical and biophysical methods to study the mechanisms of DNA replication, with particular emphasis on two complementary areas. The first area involves studies of the protein - protein and protein –DNA interactions between DNA replication initiator proteins and the chromosomal origin of replication. Utilizing bacteriophage λ as a model system, Dr. McMacken and colleagues established a reconstituted system, composed of 20 highly purified phage and bacterial proteins, that specifically initiates bidirectional DNA replication at the bacteriophage λ replication origin. These studies revealed the identity of the replicative DNA helicase used by all bacteria and demonstrated that multiprotein nucleoprotein structures with novel properties are assembled at origins prior to initiation of DNA replication. Synergistic protein – protein and protein - DNA interactions within these structures was found both to activate and open the DNA duplex at the origin as well as facilitate the loading of a DNA helicase molecule on each DNA strand to complete the initiation phase of bidirectional DNA replication. Additional experimentation revealed that partial disassembly of the preinitiation nucleoprotein complex is absolutely required for loading of replicative DNA helicases at the λ origin and that this protein remodeling event is mediated by a universally-conserved molecular chaperone system. This latter finding prompted the McMacken laboratory to undertake new lines of research that examined how cellular molecular chaperones (i) cooperate to select protein targets and (ii) harness the energy of ATP binding and hydrolysis to drive protein remodeling events.