US-France Cooperative Research: Evolution and Function of Hopanoid Lipids in Symbiotic and Thermoacidophilic Actinomycetes

University Of California-Davis, Davis CA

Investigators

Abstract

0233366 Berry This three-year award for US-France collaboration in microbial genetics involves Alison M. Berry of the University of California at Davis and Philippe Normand of the University of Claude Bernard - Lyon 1 and their students. The objectives are to study the biology of Frankia, a nitrogen-fixing prokaryote that forms root nodule symbioses and to address a key metabolic control point, the hopanoid lipid biosynthetic pathway. The production of specific hopanoid lipids in Frankia is a pivotal microorganism in that it is similar to the gram-negative rhizobia in its capacity to nodulate a group of related nitrogen-fixing plants. Frankia is related to thermoacidophilic Acidothermus cellulyticus. They will explore the role of hopanoids in symbiotic nitrogen fixation and as an adaptation to environmental stress through (1) DNA sequence information from the 17-kb Frankia genomic clone, and corresponding genes in close relatives: (2) comparisons of the profile of Frankia hopanoid lipids with that of A. Celluloyticus; and (3) environmental sampling of the thermoacidophilic actinomycetes, and expression of hopanoid genes. The information obtained in this collaboration will be used in expanded investigations of the evolution and function of hopanoid synthesis under extreme environmental conditions and by symbiotic signaling compounds. The US investigator brings to this collaboration expertise in hopanoid lipids and their importance in nitrogen fixation in Frankia. This is complemented by French expertise in Frankia phylogeny and in the use of molecular genetic tools for examining microbial communities in soils. This group also has the capacity to do proteomic analysis of Frankia. This award represents the US side of a joint proposal to the NSF and the French National Center for Scientific Research (CNRS). NSF will cover travel funds and living expenses for the US investigator and graduate students. The CNRS will support the visits of the French researchers and students to the United States. US students will benefit from the exchange of scientific techniques and experience with an international research team.