2014 ; Vol.24-10: 1413~1420
|Author||Seung-Jeung Nam, Young-Ok Kim, Tae-Kyung Ko, Jin-Ku Kang, Kwang-Hoon Chun, Joong-Hyuck Auh, Chul-Soon Lee, In-Kyu Lee, Sunghoon Park, Byung-Chul Oh|
|Place of duty||Lee Gil Ya Cancer and Diabetes Institute, Gachon University Graduate School of Medicine, Incheon 406-840, Republic of Korea|
|Title||Molecular and Biochemical Characteristics of β-Propeller Phytase from Marine Pseudomonas sp. BS10-3 and Its Potential Application for Animal Feed Additives|
J. Microbiol. Biotechnol.2014 ;
|Abstract||Phytate is an antinutritional factor that impacts the bioavailability of essential minerals such
as Ca2+, Mg2+, Mn2+, Zn2+, and Fe2+ by forming insoluble mineral-phytate salts. These insoluble
mineral-phytate salts are hydrolyzed rarely by monogastric animals, because they lack the
hydrolyzing phytases and thus excrete the majority of them. The β-propeller phytases (BPPs)
hydrolyze these insoluble mineral-phytate salts efficiently. In this study, we cloned a novel
BPP gene from a marine Pseudomonas sp. This Pseudomonas BPP gene (PsBPP) had low
sequence identity with other known phytases and contained an extra internal repeat domain
(residues 24–279) and a typical BPP domain (residues 280–634) at the C-terminus. Structurebased
sequence alignment suggested that the N-terminal repeat domain did not possess the
active-site residues, whereas the C-terminal BPP domain contained multiple calcium-binding
sites, which provide a favorable electrostatic environment for substrate binding and catalytic
activity. Thus, we overexpressed the BPP domain from Pseudomonas sp. to potentially
hydrolyze insoluble mineral-phytate salts. Purified recombinant PsBPP required Ca2+ or Fe2+
for phytase activity, indicating that PsBPP hydrolyzes insoluble Fe2+-phytate or Ca2+-phytate
salts. The optimal temperature and pH for the hydrolysis of Ca2+-phytate by PsBPP were 50°C
and 6.0, respectively. Biochemical and kinetic studies clearly showed that PsBPP efficiently
hydrolyzed Ca2+-phytate salts and yielded myo-inositol 2,4,6-trisphosphate and three
phosphate groups as final products. Finally, we showed that PsBPP was highly effective for
hydrolyzing rice bran with high phytate content. Taken together, our results suggest that
PsBPP has great potential in the animal feed industry for reducing phytates.|
|Key_word||β-propeller phytase, Pseudomonas sp, Ca2+-phytate salts|
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