Dept. Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA.
Dept. Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA.
Gene. 2014 Aug 15;547(1):91-7. doi: 10.1016/j.gene.2014.06.033. Epub 2014 Jun 18.
Cold-shock proteins (Csps) are a family of small nucleic acid-binding proteins found in 72% of sequenced bacterial genomes. Where it has been examined, at least one csp gene is required for cell viability. In Escherichia coli K-12, there are nine homologous csp genes named A-I. Regulation studies performed on individual members of this family have suggested that cspA, cspB, cspG, and cspI are cold-induced, cspC and cspE are constitutively expressed, cspD is stationary phase induced, and the induction patterns for cspF and cspH have yet to be determined. Aside from microarray studies, transcript levels from all nine csp genes have never been assayed using the same technique or in the same cells. The purpose of this study was to use quantitative RT-PCR to establish csp expression patterns for all nine csp genes at 37°C in defined rich and defined minimal media, and after a shift to 15°C for either 1h or 4h. We found that transcript levels for each of the csp genes changed throughout the growth curve. Transcripts for cspA, -B, and -E were more abundant than those detected for the other csp genes in defined rich medium. cspE mRNA levels in defined minimal medium were drastically higher than mRNA for the other csp genes. Of the nine csp genes, only cspI showed a significant increase in mRNA accumulation after cold-shock in defined rich medium. When mRNA accumulation was compared across the nine csp genes, there were more cspE transcripts in the cell than cspA, -B, -G, or -I transcripts after 1h cold-shock in either defined rich or defined minimal media. In defined minimal medium, transcription of cspA, -B, -G, and -I was induced after cold-shock.
冷休克蛋白（Csps）是一类存在于 72%已测序细菌基因组中的小核酸结合蛋白。在已研究的地方，至少有一个 csp 基因是细胞存活所必需的。在大肠杆菌 K-12 中，有九个同源的 csp 基因，分别命名为 A-I。对该家族个别成员进行的调控研究表明，cspA、cspB、cspG 和 cspI 是冷诱导的，cspC 和 cspE 是组成型表达的，cspD 是停滞期诱导的，而 cspF 和 cspH 的诱导模式尚未确定。除了微阵列研究外，从未使用相同技术或在相同细胞中测定过所有九个 csp 基因的转录水平。本研究旨在使用定量 RT-PCR 确定在 37°C 下，在定义丰富的和定义最小的培养基中，以及在 15°C 下培养 1 小时或 4 小时后，所有九个 csp 基因的 csp 表达模式。我们发现，每个 csp 基因的转录水平在整个生长曲线中都发生了变化。在定义丰富的培养基中，cspA、-B 和 -E 的转录物比其他 csp 基因的转录物更丰富。在定义最小的培养基中，cspE 的 mRNA 水平远高于其他 csp 基因的 mRNA 水平。在这九个 csp 基因中，只有 cspI 在定义丰富的培养基中冷休克后，mRNA 积累显著增加。当比较九个 csp 基因的 mRNA 积累时，在定义丰富或定义最小的培养基中，1 小时冷休克后，细胞中 cspE 的转录物比 cspA、-B、-G 或 -I 的转录物多。在定义最小的培养基中，cspA、-B、-G 和 -I 在冷休克后被转录。
