Belagal Praveen
Department of Molecular Biology, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, India.
Mol Biol Rep. 2025 Apr 30;52(1):438. doi: 10.1007/s11033-025-10460-z.
The fitA/pheS and fitB/pheT genes in E. coli have been proposed to interact with rpoB of RNA polymerase and function as transcription factors. The temperature sensitive (Ts) fitA76 mutant harbour two lesions, one in pheS (pheS5) and the other in pheT (fit95). While the pheS5 mutant was solely a translation defective, the fitA76 mutant with both the mutations (pheS5-fit95) was primarily defective at transcription. Absence of stable RNA detection was considered as the hallmark phenotype of fitA76 mutant. In order to elucidate the contribution of fit95 in the fitA76 mutant, macromolecular defect of fit95 mutation alone is studied in this investigation.
To detect macromolecular defect, the transcription abnormality of fit95 mutant per se was studied via kinetics of decay of pulse labelled RNA.
Results indicate that fit95 is not transcription defective where stable RNA could be detected, similar to pheS5 when present alone, indicating that pheS5-fit95 interface is essential in eliciting the phenotype characteristic of fitA76. The inferences drawn from these results were implicated with reference to transcription regulation by these Fit factors in vivo are discussed.
Neither the fit95 nor pheS5 when present alone was transcription defective per se but in combination (pheS5-fit95) leads to transcription defective in the fitA76 mutant.
大肠杆菌中的fitA/pheS和fitB/pheT基因被认为与RNA聚合酶的rpoB相互作用并作为转录因子发挥作用。温度敏感（Ts）fitA76突变体有两个损伤位点，一个在pheS（pheS5），另一个在pheT（fit95）。虽然pheS5突变体仅是翻译缺陷型，但具有两种突变（pheS5-fit95）的fitA76突变体主要在转录方面存在缺陷。未检测到稳定RNA被认为是fitA76突变体的标志性表型。为了阐明fit95在fitA76突变体中的作用，本研究单独研究了fit95突变的大分子缺陷。
为了检测大分子缺陷，通过脉冲标记RNA的衰变动力学研究了fit95突变体本身的转录异常。
结果表明，fit95不存在转录缺陷，能够检测到稳定RNA，这与单独存在的pheS5类似，表明pheS5-fit95界面对于引发fitA76的表型特征至关重要。讨论了从这些结果得出的推论与这些Fit因子在体内转录调控的关系。
单独存在时，fit95和pheS5本身都不存在转录缺陷，但组合在一起（pheS5-fit95）会导致fitA76突变体出现转录缺陷。
