Polyamines (putrescine, spermidine, and spermine) are the major organic polycations found in all living organisms with an essential but poorly understood biological role in cell growth. The importance of polyamines has been implicated in the biosynthesis of macromolecules including RNA, DNA, and protein. Polyamine metabolism is being extensively studied as a target for drug design in treatment of cancers and parasite infection in humans. Development of new antibiotics along this line has lagged behind, mostly due to the lack of information on polyamine catabolism in bacteria. It is the goal of this project to elucidate polyamine catabolism and regulation in P. aeruginosa, which can grow very efficiently on polyamine as the sole source of carbon and nitrogen. A complete genomic sequence annotation and the availability of DNA microarrays of this organism make P. aeruginosa an excellent model organism for the exploration of polyamine catabolism. Preliminary studies with DNA microarrays and comparative genomics approaches have identified more than eighty genes that are differentially induced by exogenous agmatine and/or putrescine. The putative biochemical functions of these genes revealed possible routes of polyamine catabolism and regulation as well as the linkage of polyamine metabolism to other metabolic activities, including organic sulfur uptake/utilization and induction of heat shock response. The specific aims of this project are: (i) to continue the characterization of these genes related to the uptake, catabolism and regulation of putrescine; and (ii) to identify additional genes involved in the catabolism of spermidine and spermine and its regulation. These will be accomplished through the use of transcriptional profiling analyses, computer-aided data mining, genetics manipulation, and enzyme purification and characterization.
Findings from this research are expected to provide novel and significant information on polyamines metabolism which could be beneficial to several fields of biology, including pharmaceutical science, bacterial pathogenesis, and agriculture. Students participating in this project will receive cross-disciplinary training in genetics, biochemistry, and bioinformatics, and thus developing an integrative view of bacterial physiology. Further, the concepts of DNA microarrays and data mining for transcriptional profiling analyses will be classroom assignments to help prepare the new generation of students in scientific work and research in the post-genomics era.
