Medina Gerardo, Juárez Katy, Valderrama Brenda, Soberón-Chávez Gloria
Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
J Bacteriol. 2003 Oct;185(20):5976-83. doi: 10.1128/JB.185.20.5976-5983.2003.
Pseudomonas aeruginosa contains two transcription regulators (LasR and RhlR) that, when complexed with their specific autoinducers (3-oxo-dodecanoyl-homoserine lactone and butanoyl-homoserine lactone, respectively) activate transcription of different virulence-associated traits. We studied the RhlR-dependent transcriptional regulation of the rhlAB operon encoding rhamnosyltransferase 1, an enzyme involved in the synthesis of the surfactant monorhamnolipid, and showed that RhlR binds to a specific sequence in the rhlAB regulatory region, both in the presence and in the absence of its autoinducer. Our data suggest that in the former case it activates transcription, whereas in the latter it acts as a transcriptional repressor of this promoter. RhlR seems to repress the transcription of other quorum-sensing-regulated genes; thus, RhlR repressor activity might be of importance in the finely regulated expression of P. aeruginosa virulence-associated traits.
铜绿假单胞菌含有两种转录调节因子（LasR和RhlR），当它们分别与各自特定的自诱导剂（3-氧代十二烷酰高丝氨酸内酯和丁酰高丝氨酸内酯）结合形成复合物时，会激活不同毒力相关性状的转录。我们研究了编码鼠李糖基转移酶1的rhlAB操纵子的RhlR依赖性转录调控，鼠李糖基转移酶1是一种参与表面活性剂单鼠李糖脂合成的酶，结果表明，无论有无自诱导剂，RhlR都能与rhlAB调控区域中的特定序列结合。我们的数据表明，在前一种情况下它激活转录，而在后一种情况下它作为该启动子的转录抑制因子发挥作用。RhlR似乎抑制其他群体感应调节基因的转录；因此，RhlR的抑制活性可能在铜绿假单胞菌毒力相关性状的精细调控表达中具有重要作用。
