Glucose-1-phosphatase (AgpE) from Enterobacter cloacae displays enhanced phytase activity.
Using a screening procedure developed for detection of phytate hydrolysing enzymes, the gene agpE encoding glucose-1-phosphatase was cloned from an Enterobacter cloacae VKPM B2254 plasmid library. Sequence analysis revealed 78% identity on nucleotide and 79% identity on peptide level to Escherichia coli glucose-1-phosphatase characterising the respective gene product as a representative of acid histidine phosphatases harbouring the RH(G/N)RXRP motif. The purified recombinant protein displayed maximum specific activity of 196 U mg(-1) protein against glucose-1-phosphate but was also active against other sugar phosphates and p-nitrophenyl phosphate. High-performance ion chromatography of hydrolysis products revealed that AgpE can act as a 3-phytase but is only able to cleave off the third phosphate group from the myo-inositol sugar ring. Based on sequence comparison and catalytic behaviour against phytate, we propose to classify bacterial acid histidine phosphatases/phytases in the three following subclasses: (1) AppA-related phytases, (2) PhyK-related phytases and (3) Agp-related phytases. A distinguished activity of 32 U mg(-1) of protein towards myo-inositol-hexa-phosphate, which is two times higher than that of E. coli Agp, suggests that possibly functional differences in terms of phytase activity between Agp- and AppA-like acid histidine phosphatases are fluent.
Herter
T
T
Bacterial Genetics, Institute of Biology , Humboldt University, Berlin, Germany.
Berezina
O V
OV
Zinin
N V
NV
Velikodvorskaya
G A
GA
Greiner
R
R
Borriss
R
R
D010832:6-Phytase / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D016972:Enterobacter cloacae / Q000201:enzymology* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny
D001426:Bacterial Proteins; D010744:Phosphoric Monoester Hydrolases; D010832:6-Phytase