Cloning and expression of pyrroloquinoline quinone (PQQ) genes from a phosphate-solubilizing bacterium Enterobacter intermedium.
A grass rhizosphere bacterium, Enterobacter intermedium (60-2G), has a strong ability to solubilize insoluble phosphate. Certain phosphate-solubilizing bacteria secrete gluconic acid for this process. The gluconic acid is produced by direct extracellular oxidation of glucose by a glucose dehydrogenase equipped with pyrroloquinoline quinone (PQQ) as a cofactor. A pqq gene cluster producing PQQ was detected in E. intermedium and this sequence conferred phosphate-solubilizing activity to Escherichia coli DH5alpha. The 6,783-bp pqq sequence had six open reading frames (pqqA, B, C, D, E, and F) and showed 50-95% homology to pqq genes of other bacteria. E. coli DH5alpha expressing the E. intermedium pqq genes solubilized phosphate from hydroxyapatite after a pH drop to pH 4.0, which paralleled in time the secretion of gluconic acid. We speculate that production of PQQ in E. coli DH5alpha expressing the pqq cluster activates an endogenous glucose dehydrogenase to permit gluconic acid secretion that solubilizes the insoluble phosphate.
Kim
Chul Hong
CH
Division of Applied Plant Science, Agricultural Plant Stress Research Center, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 500-757, Republic of Korea.
Han
Song Hee
SH
Kim
Kil Yong
KY
Cho
Baik Ho
BH
Kim
Yong Hwan
YH
Koo
Bon Sung
BS
Kim
Young Cheol
YC
D003001:Cloning, Molecular; D003470:Culture Media / Q000737:chemistry; D015342:DNA Probes; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D017886:Durapatite / Q000378:metabolism; D004754:Enterobacter / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D023061:Gene Order; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D005942:Gluconates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D045542:PQQ Cofactor / Q000096:biosynthesis* / Q000235:genetics*; D010710:Phosphates / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D012995:Solubility
D003470:Culture Media; D015342:DNA Probes; D004269:DNA, Bacterial; D005942:Gluconates; D010710:Phosphates; C008229:2-ketogluconate; D045542:PQQ Cofactor; D017886:Durapatite; C030691:gluconic acid