Bacterial Nitrogen Metabolism and Its Regulation

Bacteria can utilise a wide range of inorganic and organic nitrogen sources and the mechanisms that regulate the genes required for this metabolism are complex. We are using a variety of organisms, notably Escherichia coli, Klebsiella pneumoniae and Rhizobium etli, to study components of the nitrogen sensing and regulation systems, many of which are common to a wide range of prokaryotes. <P>
Current studies focus on the process of ammonium transport by the AmtB protein, a protein that is conserved from bacteria, through fungi and plants to lower animals. Another component being investigated is the highly conserved PII protein which is found in bacteria and plants where it acts as a signal transduction protein in nitrogen sensory pathways. <P>
In the nitrogen-fixing symbiosis between Rhizobium bacteria and legumes the control of nitrogen metabolism is particularly critical in ensuring that an effective symbiosis is maintained and we are studying this process in Rhizobium etli.