Hurme R, Berndt K D, Normark S J, Rhen M
Microbiology and Tumor Biology Center, Karolinska Institute, Stockholm, Sweden.
Cell. 1997 Jul 11;90(1):55-64. doi: 10.1016/s0092-8674(00)80313-x.
Novel utilization of the coiled-coil motif is presented that enables TlpA, an autoregulatory repressor protein in Salmonella, to sense temperature shifts directly and thereby to modulate the extent of transcription repression. Salmonella cells shifted to higher temperatures, such as those encountered at host entry, showed derepressed tlpA activity. tlpA::lacZ fusions indicated that the promoter itself is insensitive to thermal shifts and that transcription control was exerted by the autorepressor TlpA only. In vitro studies with highly purified TlpA showed concentration and temperature dependence for both fully folded conformation and function, indicating that the thermosensing in TlpA is based on monomer-to-coiled-coil equilibrium.
本文展示了卷曲螺旋基序的新用途，它使沙门氏菌中的自调控阻遏蛋白TlpA能够直接感知温度变化，从而调节转录抑制的程度。转移到较高温度（如宿主入侵时遇到的温度）的沙门氏菌细胞表现出TlpA活性的去抑制。tlpA::lacZ融合表明启动子本身对热变化不敏感，转录控制仅由自阻遏物TlpA施加。对高度纯化的TlpA进行的体外研究表明，其完全折叠的构象和功能都具有浓度和温度依赖性，这表明TlpA中的热敏性基于单体到卷曲螺旋的平衡。
