Pathway of phytate dephosphorylation by beta-propeller phytases of different origins

• Using a combination of high-performance ion chromatography analysis and kinetic studies, the pathway of myomositol hexakisphosphate dephosphorylation by the beta-propeller phytase of Shewanella oneidensis was established, which was then compared with that of Bacillus subtilis 168, Bacillus amyloliquefaciens ATCC 15841, and B. amyloliquefaciens 45 beta-propeller phytases. The data demonstrate that all of these beta-propeller phytases dephosphorylate myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(1,2,4,5,6)P-5, In,(2,4,5,6)P-4 to finally Ins(2,4,6)P-3. Thus, the beta-propeller phytases prefer the hydrolysis of every second phosphate over that of adjacent ones. This finding does not support previous phytate degradation models proposed by J. Kerovuo, J. Rouvinen, and F. Hatzack (2000. Biochem. J. 352: 623-628) and R. Greiner, A. Farouk, M. Larsson Alminger, and N.G. Carlsson (2002. Can. J. Microbiol. 48: 986-994), but seems to fit with the structural model given by S. Shin, N.C. Ha, B.C. Oh, T.K. Oh, and B.H. Oh (2001. Structure, 9: 851-858).

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering (hsv//eng)

Nyckelord

PURIFICATION

BACILLUS

Shewanella oneidensis

KLEBSIELLA-TERRIGENA

MYOINOSITOL HEXAKISPHOSPHATE DEPHOSPHORYLATION

PHOSPHATE ISOMERS

phytate degradation

ESCHERICHIA-COLI

Bacillus spp.

beta-propeller phytase

MECHANISM

myo-inositol phosphate isomers

DEGRADING ENZYME

STEREOSPECIFICITY

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