Three Amino Acids in Escherichia coli CspE Surface-exposed Aromatic Patch Are Critical for Nucleic Acid Melting Activity Leading to Transcription Antitermination and Cold Acclimation of Cells

Abstract

Cold-shock proteins of the CspA family of Escherichia coli help the cells to acclimate to low temperature conditions through an unknown mechanism. In vitro, these proteins bind to single-stranded nucleic acids and destabilize nucleic acid secondary structures. An unusual surface-exposed patch of 6 evolutionarily conserved aromatic amino acids is thought to be involved in RNA binding by the cold-shock proteins. Here we investigated the functional role of the aromatic patch in E. coli CspE by substituting individual aromatic residues with positively charged Arg residues.

Bacterial RNA Chaperones Confer Abiotic Stress Tolerance in Plants and Improved Grain Yield in Maize under Water-Limited Conditions

“…There was an approximately 10-fold reduction in fluorescence observed with the CspB_F30R mutant, suggesting that this residue is important for maintaining RNA chaperone activity. A similar result has been obtained through mutation of the identical residue in the E. coli CspE protein (Phadtare et al, 2002), and its activity in Figure 2. A single transgenic CspB event demonstrates yield improvements across multiple years of testing under water-stressed environments.…”

How Phosphotransferase System-Related Protein Phosphorylation Regulates Carbohydrate Metabolism in Bacteria

“…70,2006 PHOSPHOTRANSFERASE SYSTEM-RELATED PHOSPHORYLATION 1009 tain a histidine homologous to the phosphorylatable His-91 in E. coli EIIA Glc (47), which, however, could not be phosphorylated by PEP, EI, and HPr. Nevertheless, this histidine is important for Csp function (659). In addition, various L. casei mutants affected in CCR exhibited reduced growth rates at low temperatures compared to that of the wild-type strain.…”

RNA remodeling and gene regulation by cold shock proteins

“…The proteins carrying substitutions of these amino acids with Arg fully retain their nucleic acid binding activity, but lose the ability to cause transcription antitermination and cold acclimation of cells as they lack the melting activity. 40,77 DNA microarray analysis of the cold shock response of the wild-type to cold-shock, stationary phase, nutrient starvation and freezing, 47,48 antibiotic biosynthesis, 49 UV sensitivity, 50 regulation of expression of proteins responding to osmotic stress, oxidative stress and stationary phase (UspA, OsmY, Dps, ProP and KatG 51 ), camphor resistance and chromosome condensation, 52,53 downregulation of λ Q-mediated transcription antitermination, 54 downregulation of poly(A)-mediated 3' to 5' exonucleolytic decay by PNPase, 55 inhibition of DNA replication, 56 and tolerance to solvents such as toluene. 57 The cold-shock induction of CspA and its homologs was studied in detail and was shown to occur at the levels of transcription, mRNA stability and translation.…”