Structure-function relationship in escherichia coli RNA polymerase subunits : a case study with a-subunit

Abstract

Specific protein-protein and protein-DNA interactions govern the regulation of all cellular newlineprocesses which constitute a living cell. The basis of all essential biological functions is the newlineability of the cell to elicit the required cellular response by specific molecular interactions. newlineFor example, replication apparatus, transcription machinery, translation complexes, newlineenzyme assemblies, receptor-ligand interactions and transport pathways all mediate their newlinerespective functions by cross-talk between specific macromolecules. Protein-protein newlineinteraction is an important subset of a variety of interactions constituting biological newlineprocesses. newlineThe transcription apparatus in Escherichia coli consists of a DNA dependent RNA newlinepolymerase (RNAP) which is a multi-subunit enzyme with subunit composition of newlinea 2j3W (l)(J. Interactions within and between the subunits result in the formation of newlinecatalytically competent enzyme capable of .promoter specific initiation of transcription. newlineMoreover, specific interactions between RNAP and transcriptions activators or DNA fine newlinetune the transcription apparatus to meet the myriad cellular needs. Thus, an insight into newlineprotein-protein interactions provides a basis for understanding the highly ordered and newlineregulated process of transcription in E.coli. newlineChapter I outlines the various in vitro biochemical methods and also in particular, newlinein vivo genetic approach employed to study protein-protein interactions. Genetic newlineapproaches encompassing the various mechanisms of suppression is discussed. This newlinechapter also outlines the power of genetic suppression as a tool to probe protein-protein newlineinteractions citing recent examples, specifically in understanding structure-function newlinerelationship within multisubunit complexes, followed by a brief description of E.coli RNA newlinepolymerase and its subunits. newlineChapter II describes a method to detect Zn (II) binding proteins and the results with newlineE.coli RNA polymerase which is a Zn (II) metalloenzyme.