Myxococcus xanthus generates polyphosphates (polyPs) during starvation and forms fruiting bodies through the activity of polyphosphate kinase (Ppk). M. xanthus polyP:AMP phosphotransferase (Pap), a class II Ppk2, catalyzes the transfer of the terminal phosphate from polyP to AMP to yield ADP, but its enzymatic properties have not been investigated in detail. In this study, we found that Pap was activated by Mn²⁺ or Mg²⁺ and required higher concentrations of these ions in reactions with longer polyPs to demonstrate maximum activity. The K_m of Pap for polyP_700-1000 was significantly lower than that for shorter polyPs, but the highest catalytic constant (k_cat) was observed for polyP_60-70. When Pap was incubated with polyP_60-70 and AMP for 3 h, it first generated ADP and then gradually produced ATP, suggesting that M. xanthus Pap also has polyP:ADP phosphotransferase activity similar to that of class III Ppk2 enzymes. During starvation, the specific activity of Pap in M. xanthus was increased by 2.3–2.4-fold at days 1 and 2 of incubation. In addition, recombinant Pap in combination with M. xanthus recombinant enzymes Ppk1 or adenylate kinase (AdkA) could generate ATP from AMP and polyP_60-70. These results suggest a functional role of Pap during M. xanthus starvation, when it might act in cooperation with Ppk1 and/or AdkA to produce ATP from AMP, ADP, and polyP.

黄色粘球菌产生饥饿期间多磷酸盐（息肉），并通过多磷酸激酶（PPK）的活性子实体形式。黄色粘球菌息肉：AMP磷酸转移酶（PAP），II类Ppk2，催化从息肉AMP末端磷酸以产生ADP的转移，但它的酶学性质没有详细进行了研究。在这项研究中，我们发现Pap被Mn ²⁺或Mg ²⁺激活，并且在与更长的polyPs反应时需要更高浓度的这些离子以显示最大活性。polyP _700-1000的Pap K _m明显低于较短polyPs的K _m，但催化常数最高（k _cat）观察到polyP _60-70。当巴氏用息肉孵育_60-70和AMP 3小时，它首先产生的ADP，然后逐渐产生的ATP，这表明黄色粘球菌的巴氏还具有息肉：ADP磷酸类似于类III Ppk2酶的活性。在饥饿，巴氏的比活性黄色粘球菌在天1增加了2.3-2.4倍和温育2。另外，在与组合的重组巴氏黄色粘球菌的重组酶或Ppk1腺苷酸激酶（AdkA）可以由AMP和息肉生成ATP _60-70。这些结果表明在黄单胞菌期间Pap的功能性作用。 饥饿时，它可能与Ppk1和/或AdkA协同作用以从AMP，ADP和polyP产生ATP。