Characterization of three putative xylulose 5-phosphate/fructose 6-phosphate phosphoketolases in the cyanobacterium <i>Anabaena</i> sp. PCC 7120

<div><p>Xylulose 5-phosphate/fructose 6-phosphate phosphoketolase (Xfp) is a key enzyme in the central carbohydrate metabolism in heterofermentative bacteria, in which enzymatic property of Xfps is well characterized. This is not the case in other microbes. The cyanobacterium <i>Anabaena</i> sp. PCC 7120 possesses three putative genes encoding Xfp, <i>all1483</i>, <i>all2567</i>, and <i>alr1850</i>. We purified three putative Xfps as recombinant proteins. The results of gel filtration indicated that these proteins form homomultimer complex. All1483 and All2567 showed phosphoketolase activity, whereas Alr1850 did not show the activity. Kinetic analyses demonstrated that substrates, fructose 6-phosphate and inorganic phosphate, are cooperatively bound to enzymes positively and negatively, respectively.</p></div>