Berger F, Normand P, Potier P
Laboratoire d'Ecologie Microbienne du Sol, UMR 5557, Université Claude Bernard, Lyon I, Villeurbanne, France.
J Bacteriol. 1997 Sep;179(18):5670-6. doi: 10.1128/jb.179.18.5670-5676.1997.
By use of Arthrobacter globiformis SI55, a psychrotrophic bacterium capable of growth between -5 and +32 degrees C, we cloned and sequenced capA, a gene homologous to cspA encoding the major cold shock protein in Escherichia coli. The deduced protein sequence has a high level of identity with the sequences of other CspA-related proteins from various sources, and no particular residue or domain that could be specific to cold-adapted microorganisms emerged. We show that CapA was produced very rapidly following cold shock, but unlike its mesophilic counterparts, it was still expressed during prolonged growth at low temperature. Its synthesis is regulated at the translational level, and we showed that growth resumption following a temperature downshift correlated with CapA expression. Transient inhibitions in protein synthesis during the first stages of the cold shock response severely impaired the subsequent acclimation of A. globiformis SI55 to low temperature and delayed CapA expression. The cold shock response in A. globiformis SI55 is an adaptative process in which CapA may play a crucial role. We suggest that low-temperature acclimation is conditioned mainly by the ability of cells to restore an active translational machinery after cold shock in a process that may be different from that present in mesophiles.
利用球形节杆菌SI55（一种能够在-5至+32摄氏度之间生长的嗜冷细菌），我们克隆并测序了capA基因，它与大肠杆菌中编码主要冷休克蛋白的cspA基因同源。推导的蛋白质序列与来自各种来源的其他CspA相关蛋白的序列具有高度同一性，并且没有出现可能特定于冷适应微生物的特定残基或结构域。我们发现CapA在冷休克后很快产生，但与其嗜温对应物不同的是，在低温下长时间生长期间它仍会表达。其合成在翻译水平受到调控，并且我们表明温度下降后生长恢复与CapA表达相关。在冷休克反应的最初阶段蛋白质合成的短暂抑制严重损害了球形节杆菌SI55随后对低温的适应并延迟了CapA表达。球形节杆菌SI55中的冷休克反应是一个适应性过程，其中CapA可能起关键作用。我们认为低温适应主要取决于细胞在冷休克后恢复活跃翻译机制的能力，这个过程可能与嗜温菌中的过程不同。
