Global Protein-Level Responses of <i>Halobacterium salinarum</i> NRC-1 to Prolonged Changes in External Sodium Chloride Concentrations

Responses to changes in external salinity were examined in Halobacterium salinarum NRC-1. H. salinarum NRC-1 grows optimally at 4.3 M NaCl and is capable of growth between 2.6 and 5.1 M NaCl. Physiological changes following incubation at 2.6 M NaCl were investigated with respect to growth behavior and proteomic changes. Initial observations indicated delayed growth at low NaCl concentrations (2.6 M NaCl), and supplementation with different sugars, amino acids, or KCl to increase external osmotic pressure did not reverse these growth perturbations. To gain a more detailed insight into the adaptive responses of H. salinarum NRC-1 to changes in salinity, the proteome was characterized using iTRAQ (amine specific isobaric tagging reagents). Three hundred and nine differentially expressed proteins were shown to be associated with changes in the external sodium chloride concentration, with proteins associated with metabolism revealing the greatest response.本研究针对盐生盐杆菌（Halobacterium salinarum）NRC-1对外界盐度变化的响应展开了系统考察。该菌株的最适生长NaCl浓度为4.3 M，可在2.6 M至5.1 M的NaCl浓度范围内完成增殖。针对该菌株在2.6 M NaCl条件下培养后的生理变化，本研究从生长行为与蛋白质组变化两个维度展开探究。初步观测结果显示，在低NaCl浓度（2.6 M）环境中菌株生长出现延迟；且通过添加不同糖类、氨基酸或氯化钾以提升外界渗透压的干预手段，均未能逆转该生长紊乱现象。为更深入解析盐生盐杆菌NRC-1对盐度变化的适应性响应机制，本研究采用iTRAQ（amine specific isobaric tagging reagents，胺特异性同量异位素标记试剂）技术对其蛋白质组进行了表征分析。最终鉴定出309种与外界NaCl浓度变化相关的差异表达蛋白，其中与代谢过程相关的蛋白响应程度最为显著。