Analysis of growth phase-dependent long-range nucleoprotein complexes of nucleoid-associated proteins and their impact on gene regulation in Escherichia coli

点击翻译按钮获取中文摘要

This Project will focus on the mechanism of coordination of growth phase-dependent gene expression by the E. coli global transcriptional regulator FIS. FIS is a nucleotide-associated protein affecting transcription both by direct binding to DNA sites and also by modulating the global DNA topology. Our analyses of growth phase-dependent transcript profiles indicate that among the distinct functional groups of genes regulated by FIS are also those of transcription machinery, thus revealing a new component potentially mediating the general effect of FIS on transcription. Furthermore, our preliminary studies reveal a striking spatial-temporal pattern of fis-dependent transcript profiles. During exponential growth the transcripton activation by FIS is most evident in a megabase-size domain composing the replication origin (Ori), whereas the genes in the region composising the replication terminus (Ter) are repressed. However, the genes in the Ter region are activated on transition to stationary phase. Most of these fis-dependent genes also respond to changes of supercoiling level. Our data strongly suggest that during the bacterial growth cycle FIS coordinates gene expression by organizing transcription in distinct megabase-size chromosomal domains. The aim of this study is to unravel the mechanism of this novel organizational level of gene transcription.