The Role of SprE in E. coli Polyadenylation: A Focus on the Effect of SprE on malE, lamB, and glpTQ Operons

Abstract

In facing nutrient deprivation, E. coli cells transition from an exponential growth phase to stationary phase by adjusting genetic expression for survival in the new environment. SprE, an adaptor protein that increases in protein level in the stationary phase of E. coli cells, has a primary function of degrading RpoS (RNA polymerase sigma factor) in exponential phase and a secondary function of degrading mRNA. This project proceeded to further confirm the secondary function of SprE by analyzing mRNA and protein level changes of the malE, lamB, glpT, and glpQ transcripts in sprE mutants, as preliminary microarray data suggested that these transcripts are upregulated in the absence of SprE. While deleting SprE may cause increases in the protein level of MalE and LamB, this does not correspond to a phenotypic change in maltose metabolism. The glpTQ operon mRNA upregulation in ΔsprE was confirmed by qRT-PCR, and corresponding protein levels of GlpT can be assayed for fosfomycin resistance, as fosfomycin is known to enter through GlpT. Additionally, preliminary evidence suggests regulation of transcripts by SprE at the 3'UTR. These results provide a novel means for analyzing the polyadenylation function of SprE and expanding the understanding of E. coli stress responses in stationary phase.