Related Experiment Video
Updated: Jul 15, 2026

The Multifaceted Benefits of Protein Co-expression in Escherichia coli
Published on: February 5, 2015
Ribosomal proteins of Escherichia coli that stimulate stringent-factor-mediated pyrophosphoryl transfer in vitro
Abstract:
Guanosine tetra- and pentaphosphate, (p)ppGpp, can be synthesized in vitro in a reaction containing only the enzyme (stringent factor), salts, and substrates (nonribosomal system). This reaction is greatly stimulated upon addition of methanol (methanol system) or by ribosomes, mRNA, and tRNA (ribosome system). Here we show that several ribosomal proteins alone stimulate the synthesis of (p)ppGpp in the presence of stringent factor (protein system). The optimal ionic conditions for the ribosome and protein systems are identical. The concentration of ribosomes or any stimulating ribosomal protein required for saturation of a given concentration of stringent factor is similar. Fifty of 54 ribosomal proteins were tested for stimulation in the protein system; 15 proteins showed high activity, seven of these from the 30S ribosomal subunit and eight from the 50S subunit. The physiological relevance of this finding is discussed.
Related Concept Videos
Bacterial RNA Polymerase
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
Ribosomal RNA Synthesis
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
Coordination of Gene Expression Processes in Bacteria
Bacterial Protein Maturation
Stringent Response in E. coli
Other Stress Responses in Bacteria

