Coordinated Regulation of Gene Expression by E.coli Chromatin Proteins FIS and H-NS

Download or read book Coordinated Regulation of Gene Expression by E.coli Chromatin Proteins FIS and H-NS written by Ramesh Mavathur Nanjundaiah and published by . This book was released on 2007 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bacteria posses impressive ability to adapt to their environment. Adaptation is accomplished mainly by adjustment of the gene expression pattern. Studies on transcript profiling in E.coli demonstrated the existence of direct correlations between the global gene expression patterns and different phases. Previous work indicated that in E.coli the transcription is controlled by a global regulatory network whose main components are - DNA topoisomerases, chromatin proteins and the RNA polymerase. Aim of this project was to understand the structural mechanism of interaction of the components (DNA supercoiling and chromatin proteins) and the underlying functional coordination of gene expression in E.coli. To understand the molecular mechanism of the interplay, the problem was approached at two levels of complexity (1) global - using a novel DNA microarray-based approach combining mutations in the genes of chromatin proteins with directional changes of DNA superhelicity and (2) local - at the level of individual gene promoter, using tyrT promoter system. The study has led us to propose that the global transcription is spatiotemporally coordinated by the differential distribution of two types of information, 'analog' and 'digital'. The digital or discontinuous property of information is manifest in the pattern of expressed genes depending on the distribution of the analog component - DNA supercoiling - in different parts of the genome. The analog component is continuously converted in the pattern of expressed genes and vice versa, thereby modulating the physiology to a dynamic equilibrium. On the example of tyrT promoter we demonstrate how the sequence organization of the promoter determines the supercoiling sensitivity of the promoters. We also show that the transcription from a strong promoter, like tyrT, is a consequence of the local effect of binding of chromatin protein FIS at the promoter and the general effect of FIS on the average superhelical density of the DNA.