当前位置: X-MOL 学术BBA Gen. Subj. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Constitutive inorganic pyrophosphatase as a reciprocal regulator of three inducible enzymes in Escherichia coli
Biochimica et Biophysica Acta (BBA) - General Subjects ( IF 3 ) Pub Date : 2020-10-11 , DOI: 10.1016/j.bbagen.2020.129762
Natalia N. Vorobyeva , Svetlana A. Kurilova , Anna V. Vlasova , Viktor A. Anashkin , Tatiana I. Nazarova , Elena V. Rodina , Alexander A. Baykov

Background

Previous studies have demonstrated the formation of stable complexes between inorganic pyrophosphatase (PPase) and three other Escherichia coli enzymes – cupin-type phosphoglucose isomerase (cPGI), class I fructose-1,6-bisphosphate aldolase (FbaB) and l-glutamate decarboxylase (GadA).

Methods

Here, we determined by activity measurements how complex formation between these enzymes affects their activities and oligomeric structure.

Results

cPGI activity was modulated by all partner proteins, but none was reciprocally affected by cPGI. PPase activity was down-regulated upon complex formation, whereas all other enzymes were up-regulated. For cPGI, the activation was partially counteracted by a shift in dimer ⇆ hexamer equilibrium to inactive hexamer. Complex stoichiometry appeared to be 1:1 in most cases, but FbaB formed both 1:1 and 1:2 complexes with both GadA and PPase, FbaB activation was only observed in the 1:2 complexes. FbaB and GadA induced functional asymmetry (negative kinetic cooperativity) in hexameric PPase, presumably by favoring partial dissociation to trimers.

Conclusions

These four enzymes form all six possible binary complexes in vitro, resulting in modulated activity of at least one of the constituent enzymes. In five complexes, the effects on activity were unidirectional, and in one complex (FbaB⋅PPase), the effects were reciprocal. The effects of potential physiological significance include inhibition of PPase by FbaB and GadA and activation of FbaB and cPGI by PPase. Together, they provide a mechanism for feedback regulation of FbaB and GadA biosynthesis.

General significance

These findings indicate the complexity of functionally significant interactions between cellular enzymes, which classical enzymology treats as individual entities, and demonstrate their moonlighting activities as regulators.



中文翻译:

组成型无机焦磷酸酶作为大肠杆菌中三种可诱导酶的相互调节剂

背景

先前的研究表明,无机焦磷酸酶(PPase)与其他三种大肠杆菌酶之间形成稳定的复合物-铜型磷酸葡萄糖异构酶(cPGI),I类果糖-1,6-双磷酸醛缩酶(FbaB)和1-谷氨酸脱羧酶( GadA)。

方法

在这里,我们通过活性测量来确定这些酶之间的复杂形成如何影响其活性和寡聚结构。

结果

cPGI的活性受所有伴侣蛋白的调节,但没有一个相互受到cPGI的影响。复合物形成后,PPase活性被下调,而所有其他酶被上调。对于cPGI,激活被二聚体⇆六聚体平衡转变为非活性六聚体部分抵消。在大多数情况下,复合物化学计量比看来是1:1,但是FbaB与GadA和PPase形成了1:1和1:2的复合物,仅在1:2的复合物中观察到FbaB的活化。FbaB和GadA可能通过促进三聚体的部分解离而在六聚PPase中引起功能不对称(负动力学协同性)。

结论

这四种酶在体外形成所有六个可能的二元复合物,从而导致至少一种组成酶的活性被调节。在五种复合物中,对活性的影响是单向的,而在一种复合物中(FbaB·PPase),其影响是相反的。潜在的生理学意义包括:FbaB和GadA抑制PPase,PPase激活FbaB和cPGI。它们共同提供了FbaB和GadA生物合成的反馈调节机制。

一般意义

这些发现表明细胞酶之间功能上重要相互作用的复杂性,经典酶学将其视为单个实体,并证明了它们作为调节剂的月光活动。

更新日期:2020-10-30
down
wechat
bug