ARCHAEAL GRPE - TRANSCRIPTION IN 2 DIFFERENT MORPHOLOGIC STAGES OF METHANOSARCINA-MAZEI AND COMPARISON WITH DNAK AND DNAJ

Transcription of the heat shock gene grpE was studied in two different morphologic stages of the archaeon Methanosarcina mazei S-6 that diff er in resistance to physical and chemical traumas: single cells and pa ckets. While single cells are directly exposed to environmental change s, such as temperature elevations, cells in packets are surrounded by intercellular and peripheral material that keeps them together in a gl obular 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 transcri pt levels in packets were observed after the longest heat shock tested , 60 min. The same response profiles were demonstrated by primer exten sion experiments and S1 nuclease analysis. A comparison of the grpE re sponse to heat shock with those of dnaK and dnaJ showed that the grpE transcript level was the most increased, closely followed by that of t he dnaK transcript, with that of the dnaJ gene being the least augment ed. Transcription of grpE started at the same site under normal and he at shock temperatures, and the transcript was consistently similar to 700 bases long. Codon usage patterns revealed that the three archaeal genes use most codons and have the same codon preference for 61% of th e amino acids.