Yamanaka K, Fang L, Inouye M
Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA.
Mol Microbiol. 1998 Jan;27(2):247-55. doi: 10.1046/j.1365-2958.1998.00683.x.
CspA was originally found as the major cold-shock protein in Escherichia coli, consisting of 70-amino-acid residues. It forms a beta-barrel structure with five anti-parallel beta-strands and functions as an RNA chaperone. Its dramatic but transient induction upon cold shock is regulated at the level of transcription, mRNA stability and translation. Surprisingly, E. coli contains a large CspA family, consisting of nine genes from cspA to cspI. Phylogenetic analysis of these gene products and the cold-shock domain of human YB-1 protein reveals that there are two major branches in the evolution of CspA homologues: one branch for CspF and CspH, and another for all the other known CspA homologues from both prokaryotes and eukaryotes. The locations of these genes on the E. coli chromosome suggest that the large CspA family probably resulted from a number of gene duplications and, after subsequent adaptation, resulted in specific groups of genes that respond to different environmental stresses; for example, cspA, cspB and cspG for cold-shock stress and cspD for nutritional deprivation. The E. coli CspA family will be discussed in terms of their structures and functions, and their gene structures and regulation.
CspA最初被发现是大肠杆菌中的主要冷休克蛋白，由70个氨基酸残基组成。它形成一个具有五条反平行β链的β桶结构，并作为一种RNA伴侣发挥作用。其在冷休克时显著但短暂的诱导是在转录、mRNA稳定性和翻译水平上受到调控的。令人惊讶的是，大肠杆菌含有一个庞大的CspA家族，由从cspA到cspI的九个基因组成。对这些基因产物以及人类YB - 1蛋白的冷休克结构域进行系统发育分析表明，在CspA同源物的进化中有两个主要分支：一个分支是CspF和CspH，另一个分支是来自原核生物和真核生物的所有其他已知CspA同源物。这些基因在大肠杆菌染色体上的位置表明，庞大的CspA家族可能是由多次基因复制产生的，并且在随后的适应过程中，产生了对不同环境压力作出反应的特定基因组；例如，cspA、cspB和cspG应对冷休克压力，而cspD应对营养剥夺。将从大肠杆菌CspA家族的结构和功能、基因结构及其调控方面进行讨论。
