Glycogen was described as a temporal storage molecule in rhodococci, interconnecting lipids and carbon availability. The Rhodococcus jostii ADP-glucose pyrophosphorylase (ADP-GlcPPase) kinetic and regulatory properties support this role. Curiously, the enzyme uses glucosamine-1P as alternative substrate. Herein, we report the in-depth study of glucosamine-1P activity and its regulation in two rhodocoocal ADP-GlcPPases, finding that glucosamine-6P (representing a metabolic carbon/nitrogen node) is a critical activator, then reinforcing the role of glycogen as an “intermediary metabolite” in rhodococci. Glucosamine-1P activity in rhodococcal ADP-GlcPPases responds to activation by metabolites improving their catalytic performance, strongly suggesting its metabolic feasibility. This work supports a scenario for new molecules/metabolites discovery and hypothesizes on evolutionary mechanisms underlying enzyme promiscuity opening novel metabolic features in (actino)bacteria.

糖原被描述为红球菌中的暂时性储存分子，将脂质和碳的可利用性联系在一起。在红球菌jostiiADP-葡萄糖焦磷酸化酶（ADP-GlcPPase）的动力学和调节特性支持这一作用。奇怪的是，该酶使用氨基葡萄糖-1P作为替代底物。在本文中，我们报告了对两种糖球蛋白ADP-GlcPPases中的葡萄糖胺1P活性及其调控的深入研究，发现葡萄糖胺6P（代表代谢性碳/氮节点）是关键的激活剂，从而增强了糖原的作用红球菌中的“中间代谢物”。红球菌ADP-GlcPPases中的葡萄糖胺1P活性对代谢物的激活作出反应，从而改善了其催化性能，强烈暗示了其代谢的可行性。这项工作为新的分子/代谢物的发现提供了一种方案，并假设了酶混杂的基础上进化出（肌动）细菌新的代谢特征的进化机制。