Monday, July 27, 2009 - 3:00 PM
S32

Bacterial inositol-catabolizing enzymes: knowns, unknowns, and unknown unknowns

David R. J. Palmer, Chemistry, University of Saskatchewan, 11o Science Place, Saskatoon, SK S7N 5C9, Canada

myo-Inositol is an abundant natural product that many environmental bacteria, including Bacillus subtilis, can use as sole carbon source. The iol operon for inositol catabolism has been identified in several organisms, and most of the gene products have specific metabolic functions assigned. Recently, iol operons have been identified and studied in bacteria as diverse as Lactobacillus casei and Salmonella typhimurium. The first step in inositol catabolism is catalyzed by inositol dehydrogenase (IDH), an NAD+-dependent oxidoreductase that yields scyllo-inosose. We have studied the structure and function of B. subtilis IDH, and discovered an unexpected, broad substrate spectrum. Furthermore, initial investigation of a putative IDH from L. plantarum has revealed surprising differences between these two enzymes. These results will be discussed in the context of how much we do and do not know about prokaryotic inositol metabolism.