The coming of age of the LeuO regulator.
LeuO is a quiescent genetic regulator present in many bacteria, which forms part of the H-NS regulon. LeuO in turn has been proposed to activate a subset of genes of the regulon by antagonizing H-NS. In the paper by Dillon et al., binding of LeuO to the S. Typhimurium genome was observed by ChIP-chip to some of the previously described LeuO-regulated genes, upon growth under stress conditions. However, studies at a higher LeuO concentration from a cloned inducible promoter rendered many more binding sites, pointing towards the importance of the abundance of the regulator in the cell, in a given moment. Binding of LeuO was observed not only to intergenic sequences, but in the majority of cases to intragenic sequences, and co-binding was observed with H-NS in many sites and with RNA polymerase to the majority of sites. The authors define a binding motif that allowed the detection of several other LeuO-regulated genes that were not detected by ChIP-chip, which were possibly missed because LeuO binds and bridges distal sites, in those instances. The observations reported open new questions regarding the mode of action for LeuO.
Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México.
Ismael
I
Hernández-Lucas
Edmundo
E
Calva
D015964:Gene Expression Regulation, Bacterial; D012486:Salmonella typhimurium / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism*
D014157:Transcription Factors