Ribonucleotide reductases (RNRs) catalyze the conversion of ribonucleotides to deoxyribonucleotides in all organisms and provide the monomeric precursors required for DNA replication and repair. They play an essential role in coordinating chromosomal replication and cell division. Many bacteria and archaea posses more than one kind of RNR. The existence of multiple classes of RNRs within a single organism presumably reflects its physiological needs and evolutionary history. Thus, facultative aerobes may possess RNRs dedicated to aerobic and anaerobic growth. Some bacteria possess one or more RNRs that can function in aerobic conditions and others have alternative RNRs that can function in anaerobic conditions. For example, aerobic Streptomyces spp possess class Ia and class II RNRs and Pseudomonas spp possess all three RNR classes. What then determines which of a number of alternative RNR systems is used for growth, persistence and survival in different physiological and environmental conditions? The occurrence in bacteria of multiple RNRs poses important questions regarding the mechanisms by which they are regulated and the conditions in which they are expressed. I will attempt to address some of these issues in this presentation, and will focus on some of the newly discovered transcriptional regulatory mechanisms that control the bacterial RNR gene expression.
Yair Aharonowitz is a Professor of Microbiology and Biotechnology at Tel Aviv University (TAU) and a Fellow of the American Academy of Microbiology. He was a research fellow in biochemical engineering at MIT (USA), and since 1976 he is a member of the academic staff of TAU. He was an EMBO fellow at Oxford University, an Alberta Heritage Fellow at the University of Alberta, a visiting professor at the Karolinska Institute, Stockholm, and at the University of British Columbia, Vancouver. Professor Aharonowitz research interests include the molecular genetics and biosynthesis of antibiotics, molecular biology of microbial pathogens and the development of new targets for new antibiotics, and metabolic regulation at the transcription level by transcription factors and riboswitch mechanisms.
Moderation: Professor Dr. Michael Hecker