Regulatory exaptation of the catabolite repression protein (Crp)-cAMP system in Pseudomonas putida
Regulatory exaptation of the catabolite repression protein (Crp)-cAMP system in Pseudomonas putida
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DOI：
10.1111/j.1462-2920.2010.02331.x
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发表时间：
2011-02-01
影响因子：
5.1
通讯作者：
de Lorenzo, Victor
中科院分区：
文献类型：
--
作者：
Milanesio, Paola;Arce-Rodriguez, Alejandro;de Lorenzo, Victor
土壤细菌恶臭假单胞菌KT2440的基因组编码大肠杆菌分解代谢物抑制蛋白（crp）和腺苷酸环化酶（cyaA）基因的单一同源物。在体内用Dictyostelium生物传感器检测不到p.p putida细胞形成的cAMP水平。cyaA (P。putida)基因在体内转录，但未能补充大肠杆菌cyaA突变体缺乏麦芽糖消耗，从而表明cyaA(P。Putida)在异源宿主中翻译不良或无功能。然而，CyaA(P。通过表达cyaA(P。在一种超敏感的大肠杆菌菌株中含有恶臭菌（putida）基因。另一方面，crp(P。putida)基因恢复了大肠杆菌等效crp突变体的代谢能力，但在双crp/cyaA菌株中没有，这表明调节这种功能的能力需要cAMP。为了阐明恶臭p.p . putida中Crp/cAMP系统的广度，我们产生了Crp和cyaA突变体，并通过一系列表型测试来识别其总体代谢特性和耐压能力。这些分析表明，每个基因的丢失在大多数（但不是全部）情况下导致相同的表型行为，表明协同功能。出乎意料的是，这些突变都没有影响到可被恶臭杆菌用作生长底物的碳化合物，突变体仅在使用各种二肽作为氮源时受到损害。此外，缺乏crp或cyaA对细胞的毛生长指纹几乎没有影响。与大肠杆菌相比，恶臭杆菌的Crp-cAMP系统的生理特征较差，这暴露了一种调节作用的情况，即为特定功能进化的特性被用于新用途的过程。
P>The genome of the soil bacterium Pseudomonas putida KT2440 encodes singular orthologues of genes crp (encoding the catabolite repression protein, Crp) and cyaA (adenylate cyclase) of Escherichia coli. The levels of cAMP formed by P. putida cells were below detection with a Dictyostelium biosensor in vivo. The cyaA(P.putida) gene was transcribed in vivo but failed to complement the lack of maltose consumption of a cyaA mutant of E. coli, thereby indicating that cyaA(P.putida) was poorly translated or rendered non-functional in the heterologous host. Yet, generation of cAMP by CyaA(P.putida) could be verified by expressing the cyaA(P.putida) gene in a hypersensitive E. coli strain. On the other hand, the crp(P.putida) gene restored the metabolic capacities of an equivalent crp mutant of E. coli, but not in a double crp/cyaA strain, suggesting that the ability to regulate such functions required cAMP. In order to clarify the breadth of the Crp/cAMP system in P. putida, crp and cyaA mutants were generated and passed through a battery of phenotypic tests for recognition of gross metabolic properties and stress-endurance abilities. These assays revealed that the loss of each gene led in most (but not all) cases to the same phenotypic behaviour, indicating a concerted functionality. Unexpectedly, none of the mutations affected the panel of carbon compounds that can be used by P. putida as growth substrates, the mutants being impaired only in the use of various dipeptides as N sources. Furthermore, the lack of crp or cyaA had little influence on the gross growth fingerprinting of the cells. The poor physiological profile of the Crp-cAMP system of P. putida when compared with E. coli exposes a case of regulatory exaptation, i.e. the process through which a property evolved for a particular function is co-opted for a new use.