CspA, the major cold shock protein of Escherichia coli, negatively regulates its own gene expression

Abstract

When the gene for CspA, the major cold shock protein of Escherichia coli, was disrupted by a novel positive/negative selection method, the ⌬cspA cells did not show any discernible growth defect at either 37 or 15°C. By two-dimensional gel electrophoresis, total protein synthesis was analyzed after temperature downshift in the ⌬cspA strain. The production of the CspA homologs CspB and CspG increased, and the duration of their expression was prolonged, suggesting that both CspB and CspG compensate for the function of CspA in the absence of CspA during cold shock adaptation. Interestingly, the production of the 159-base 5-untranslated region (5-UTR) of cspA from the chromosomal cspA::cat gene, detected by primer extension, failed to be repressed after cold shock. When an independent system to produce CspA was added to the ⌬cspA strain, the 5-UTR production for the cspA::cat gene was significantly reduced compared to that of the ⌬cspA strain. By examining the expression of translationally fused cspA and cspB genes to lacZ in the ⌬cspA strain, it was found that cspA is more strongly regulated by CspA than cspB is. We showed that the increased expression of the 5-UTR of the cspA mRNA in the ⌬cspA strain occurred mainly at the level of transcription and, to a certain extent, at the level of mRNA stabilization. The mRNA stabilization in the ⌬cspA strain was observed for other mRNAs, supporting the notion that CspA functions as an mRNA chaperone to destabilize secondary structures in mRNAs.

Global effects of homocysteine on transcription in Escherichia coli: induction of the gene for the major cold-shock protein, CspA

“…Escherichia coli strain Frag1 (F 2 thi rha lac gal) was from our frozen stocks. Frag1(pMM016) was generated by transformation of Frag1 with plasmid pMM016, which carries a cspA : : lacZ translational fusion (Bae et al, 1997). All growth experiments were carried out at 37 uC with aeration in a minimal medium (MM) that was adjusted to pH 6?0.…”

“…Next we used a cspA : : lacZ translational fusion, carried on plasmid pMM016 (Bae et al, 1997), to measure the expression of cspA in response to Hcy. b-Galactosidase activity was measured in control and Hcy-treated (0?5 mM) cultures of Frag1(pMM016) at suitable time intervals before and for 3 h after the addition of Hcy.…”

RNA single strands bind to a conserved surface of the major cold shock protein in crystals and solution

“…This sequence forms a stable stem-loop structure and stabilizes the mRNA at low temperature (Xia et al 2002). The cold box may be the target for CSP autoregulation by binding of CspA to its own mRNA (Jiang et al 1996;Bae et al 1997;Mitta et al 1997;Fang et al 1998;Graumann and Marahiel 1998;Horn et al 2007) although this concept was questioned in a recent study (Giuliodori et al 2010).…”

The Cold Box Stem-loop Proximal to the 5′-End of theEscherichia coli cspA Gene Stabilizes Its mRNA at Low Temperature

“…Effect of Cold Box Mutations on the Induction of a cspA-lacZ Fusion Reporter Gene-Because CspA regulates its own gene expression and may act on the Cold Box region (6,14,16), results obtained from mutations on the cspA gene may have been affected by its own gene product. Therefore, we next attempted to confirm the results presented above by examining the expression of a reporter gene in the absence of CspA.…”

“…Eight other cspA homologous genes, cspB to cspI, have been identified in the E. coli genome; thus, E. coli contains a large cspA family consisting of nine members (5). CspA is not essential at both optimal and low temperatures (6), apparently as a result of substantial functional redundancy of CspA family members. Nevertheless, a ⌬cspA⌬cspB⌬cspE⌬cspG quadruple deletion strain is cold-sensitive and shows multiple defects at low temperature; therefore, the CspA family is indispensable for E. coli to adapt to cold-shock stress (7).…”