Characterization of a monomeric heat-labile classical alkaline phosphatase from Anabaena sp. PCC7120.
Alkaline phosphatases (APs), known inducible enzymes of the Pho regulon and poorly characterized in cyanobacteria, hydrolyze phosphomonoesters to produce inorganic phosphate (P(i)) during P(i) starvation. In this study, two predicted alkaline phosphatase genes in the genome of Anabaena sp. PCC 7120, all2843 and alr5291, were apparently induced during P(i) starvation. Sequence analysis showed that alr5291 encodes a protein that is an atypical alkaline phosphatase like other cyanobacteria PhoAs, but the protein encoded by all2843 is very similar to the classical PhoAs, such as Escherichia coli alkaline phosphatase (EAP). To date, there have been no reports about classical phoA in cyanobacterial genomes. The alkaline phosphatase AP(A), coded by all2843, is characterized as a metalloenzyme containing Mg2+ and Zn2+ with molar ratio of 1 : 2. Site-directed mutagenesis analysis indicated that, though the active center of AP(A) is highly conserved in comparison with EAP, differences do exist between AP(A) and EAP in metal ion coordination. Besides, biochemical analysis revealed that AP(A) is a monomeric protein and inactivated rapidly at 50 degrees C. These results suggest that AP(A) is the first monomeric heat-labile classical PhoA found in cyanobacteria.
Luo
Ming
M
State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China. luoming1976@yahoo.cn
Guo
Yong-Chao
YC
Deng
Jiao-Yu
JY
Wei
Hong-Ping
HP
Zhang
Zhi-Ping
ZP
Leng
Yan
Y
Men
Dong
D
Song
Li-Rong
LR
Zhang
Xian-En
XE
Zhou
Ya-Feng
YF
D000469:Alkaline Phosphatase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D017033:Anabaena / Q000145:classification / Q000201:enzymology*; D020134:Catalytic Domain; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010710:Phosphates / Q000494:pharmacology; D010802:Phylogeny; D016415:Sequence Alignment; D013696:Temperature
D008670:Metals; D010710:Phosphates; D000469:Alkaline Phosphatase