Diversification and evolution of L-myo-inositol 1-phosphate synthas

L-myo-Inositol 1-phosphate synthase (MIPS, EC 5.5.1.4), the key enzyme in the inositol and phosphoinositide biosymbetic pathway, is present throughout evolutionarily diverse organisms and is considered an ancient protein/gene. Analysis by multiple sequence alignment, phylogenetic tree generation and comparison of newly determined crystal structures provides new insight into the origin and evolutionary relationships among the various MIPS proteins/genes. The evolution of the MIPS protein/gene among the prokaryotes seems more diverse and complex than amongst the eukaryotes. However, conservation of a 'core catalytic structure' among the MIPS proteins implies an essential function of the enzyme in cellular metabolism throughout the biological kingdom. (C) 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.