Structure/function analysis of abundance and transmission mechanism of genetic information invlolved in the biosynthesis of multi-catalytic site enzyme

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The intracellular alginate lyases I,II, and III are coded by one gene and produced through sequential post-translational reactions from a common pre-cursor protein Po : Po → I + 5 kDa peptide, I → II +III. The protease-like activity of I is completely inhibited by EDTA or O- phnonthroline, thus indicates that the I is a multi- catalytic site enzyme currying II, III, and protease. The protease site on I is thought to be created through the excision of N-terminal 5 kDa peptide from Po, since Po has no protease activity. An important biological problem is then raised as to how the protease site is generated and how / where the information is described in the base and amino acid sequences. The clarification of these addresses may lead to the postulation of a novel theory concerning the abundance of information contained in a gene. To solve the problems, the knowleges on the structure / function relationship of alginate lyases I, II, and III, as well as their precursor protein Po. Among these, the structure / function of III was completely analyzed through X-ray crystallography and detailed lyase reaction mechanism was clarified. Especially, a novel β-elimination reaction mechanism involving Tyr residue, but not His, was constructed with an emphasis of Low-Barrier Hydrogen Bond Theory.