In:
Canadian Journal of Microbiology, Canadian Science Publishing, Vol. 52, No. 8 ( 2006-08-01), p. 759-768
Abstract:
For the first time a dual pathway for dephosphorylation of myo-inositol hexakisphosphate by a histidine acid phytase was established. The phytate-degrading enzyme of Klebsiella terrigena degrades myo-inositol hexakisphosphate by stepwise dephosphorylation, preferably via D-Ins(1,2,4,5,6)P 5 , D-Ins(1,2,5,6)P 4 , D-Ins(1,2,6)P 3 , D-Ins(1,2)P 2 and alternatively via D-Ins(1,2,4,5,6)P 5 , Ins(2,4,5,6)P 4 , D-Ins(2,4,5)P 3 , D-Ins(2,4)P 2 to finally Ins(2)P. It was estimated that more than 98% of phytate hydrolysis occurs via D-Ins(1,2,4,5,6)P 5 . Therefore, the phytate-degrading enzyme from K. terrigena has to be considered a 3-phytase (EC 3.1.3.8). A second dual pathway of minor importance could be proposed that is in accordance with the results obtained by analysis of the dephosphorylation products formed by the action of the phytate-degrading enzyme of K. terrigena on myo-inositol hexakisphosphate. It proceeds preferably via D-Ins(1,2,3,5,6)P 5 , D-Ins(1,2,3,6)P 4 , Ins(1,2,3)P 3 , D-Ins(2,3)P 2 and alternatively via D-Ins(1,2,3,5,6)P 5 , D-Ins(2,3,5,6)P 4 , D-Ins(2,3,5)P 3 , D-Ins(2,3)P 2 to finally Ins(2)P. D-Ins(2,3,5,6)P 4 , D-Ins(2,3,5)P 3 , and D-Ins(2,4)P 2 were reported for the first time as intermediates of enzymatic phytate dephosphorylation. A role of the phytate-degrading enzyme from K. terrigena in phytate breakdown could not be ruled out. Because of its cytoplasmatic localization and the suggestions for substrate recognition, D-Ins(1,3,4,5,6)P 5 might be the natural substrate of this enzyme and, therefore, may play a role in microbial pathogenesis or cellular myo-inositol phosphate metabolism.Key words: myo-inositol phosphate isomers, phytate-degrading enzyme, phytate, phytase, Klebsiella terrigena.
Type of Medium:
Online Resource
ISSN:
0008-4166
,
1480-3275
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
2006
detail.hit.zdb_id:
280534-0
detail.hit.zdb_id:
1481972-7
SSG:
12
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