A mutant strain of Salmonella bacteria carries a mutation of the rho protein that has full activity at 37°C but is completely inactivated when the mutant strain is grown at 40°C. Speculate about the kind of differences you would expect to see if you compared a broad spectrum of mRNAs from the mutant strain grown at 37°C and the same spectrum of mRNAs from the strain when grown at 40°C.

Key Concepts

Rho Protein Function

The Rho protein is a transcription termination factor in bacteria that plays a crucial role in regulating gene expression. It facilitates the termination of transcription by recognizing specific RNA sequences, allowing for the proper release of RNA polymerase from the DNA template. In the context of the mutant strain, the activity of Rho at different temperatures directly influences the stability and abundance of mRNAs produced.

Temperature Effects on Protein Activity

Temperature can significantly affect protein structure and function, as proteins are sensitive to thermal changes. At optimal temperatures, proteins maintain their functional conformation, while deviations can lead to denaturation or loss of activity. In this case, the Rho protein's full activity at 37°C suggests that the mutant strain can effectively terminate transcription, whereas the inactivation at 40°C may result in altered mRNA profiles due to prolonged transcription of certain genes.

mRNA Profiling

mRNA profiling involves analyzing the expression levels of various mRNAs within a cell, providing insights into gene expression patterns under different conditions. By comparing mRNA profiles from the mutant strain at 37°C and 40°C, one can identify which genes are upregulated or downregulated due to the Rho protein's activity. This comparison can reveal the impact of temperature on gene expression and the potential consequences of the mutation on cellular function.