Bohg A, Ristow H
Institut für Pflanzenphysiologie, Zellbiologie und Mikrobiologie, Freie Universität Berlin, Federal Republic of Germany.
Eur J Biochem. 1987 Dec 30;170(1-2):253-8. doi: 10.1111/j.1432-1033.1987.tb13693.x.
Using the [3H]trimethylpsoralen photobinding method [Sinden, R.R., Carlson, J.O. & Pettijohn, D.E. (1980) Cell 21, 773-783], a decrease in unrestrained torsional tension of DNA was detected in Bacillus brevis cells when they had entered the sporulation phase. This decrease in superhelicity was found in cells which synthesized the peptide antibiotic tyrocidine and which were stimulated to sporulate. Fluctuations in superhelicity probably reflect a highly complicated picture of tension-relaxing and tension-inducing activities. Addition of tyrocidine to vegetative cells reduced by one-half the torsional tension from DNA, whereas ethidium bromide relaxes DNA completely. Cross-links between DNA and tyrocidine were introduced with ultraviolet light in vitro and in vivo indicating that the modulation of the DNA conformation in the cell may in fact be due to a DNA-tyrocidine interaction. In a growing B. brevis culture exogenous [3H]tyrocidine could only be photobound to DNA after the cells had entered the sporulation phase. Our results could mean that the peptide antibiotic tyrocidine is active in B. brevis on the DNA level as one regulatory factor controlling DNA functions.
采用[3H]三甲基补骨脂素光结合法[Sinden, R.R., Carlson, J.O. & Pettijohn, D.E. (1980) Cell 21, 773 - 783]，在短短芽孢杆菌细胞进入芽孢形成期时，检测到DNA无约束扭转张力降低。在合成肽抗生素短杆菌酪肽并被刺激形成芽孢的细胞中发现了这种超螺旋度的降低。超螺旋度的波动可能反映了张力松弛和张力诱导活动的高度复杂情况。向营养细胞中添加短杆菌酪肽可使DNA的扭转张力降低一半，而溴化乙锭则可使DNA完全松弛。在体外和体内用紫外线诱导DNA与短杆菌酪肽之间形成交联，这表明细胞中DNA构象的调节实际上可能是由于DNA与短杆菌酪肽的相互作用。在生长的短短芽孢杆菌培养物中，只有在细胞进入芽孢形成期后，外源性[3H]短杆菌酪肽才能光结合到DNA上。我们的结果可能意味着肽抗生素短杆菌酪肽在短短芽孢杆菌中在DNA水平上作为控制DNA功能的一种调节因子发挥作用。
