|Budget Amount *help
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥2,900,000 (Direct Cost: ¥2,900,000)
Polysaccharide-degrading enzymes including chariness, chitosanases, β-1, 3-glucanse, vAL-1, and vAL-2 are encoded by chloroviruses (Phycodnaviridae). These enzymes are expressed during infection and function at the initial stage as well as the final stage of the viral replication cycle. The vChti-1 chitinase of CVK2, a virus isolated in Kyoto, Japan, has a tandem array of two catalytic domains, each of which shows a different fashion of enzyme activity. Two size-different vChta-1 chitosanases are produced from a single gene by a read-through mechanism: the larger protein with a virion-targetting signal is incorporated into the virus particle, functioning at the beginning of the infection while the smaller protein is expressed late in infection and aids in the digestion of the host cell wall prior to the release of the viruses. The cAL-1 algal lytic enzyme digests the Chlorella cell wall, releasing acidic sugars, probably uronic acids. All of these enzymes are supposed to function cooperatively to digest complex structures and compositions of the host Chlorella cell wall.