Conway De Macario E, Clarens M, Macario A J
Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany.
J Bacteriol. 1995 Feb;177(3):544-50. doi: 10.1128/jb.177.3.544-550.1995.
Transcription of the heat shock gene grpE was studied in two different morphologic stages of the archaeon Methanosarcina mazei S-6 that differ in resistance to physical and chemical traumas: single cells and packets. While single cells are directly exposed to environmental changes, such as temperature elevations, cells in packets are surrounded by intercellular and peripheral material that keeps them together in a globular structure which can reach several millimeters in diameter. grpE transcript levels determined by Northern (RNA) blotting peaked after a 15-min heat shock in single cells. In contrast, the highest transcript levels in packets were observed after the longest heat shock tested, 60 min. The same response profiles were demonstrated by primer extension experiments and S1 nuclease analysis. A comparison of the grpE response to heat shock with those of dnaK and dnaJ showed that the grpE transcript level was the most increased, closely followed by that of the dnaK transcript, with that of the dnaJ gene being the least augmented. Transcription of grpE started at the same site under normal and heat shock temperatures, and the transcript was consistently approximately 700 bases long. Codon usage patterns revealed that the three archaeal genes use most codons and have the same codon preference for 61% of the amino acids.
在古菌马氏甲烷八叠球菌S-6的两个不同形态阶段研究了热休克基因grpE的转录情况，这两个阶段对物理和化学损伤的抗性不同：单细胞和细胞包。单细胞直接暴露于环境变化，如温度升高，而细胞包中的细胞被细胞间和外周物质包围，这些物质将它们保持在直径可达几毫米的球状结构中。通过Northern（RNA）印迹法测定的grpE转录水平在单细胞热休克15分钟后达到峰值。相比之下，在最长60分钟的热休克测试后，细胞包中观察到最高转录水平。引物延伸实验和S1核酸酶分析也显示了相同的反应模式。将grpE对热休克的反应与dnaK和dnaJ的反应进行比较，结果表明grpE转录水平增加最多，紧随其后的是dnaK转录本，而dnaJ基因的增加最少。在正常温度和热休克温度下，grpE的转录起始于同一位置，转录本长度始终约为700个碱基。密码子使用模式表明，这三个古菌基因使用大多数密码子，并且对61%的氨基酸具有相同的密码子偏好。
