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Thermus sp. GH5 is an aerobic thermophilic bacterium with optimal growth at 70-75°C isolated from a hot spring in Ardabil, North West province of Iran. Due to industrial and biotechnological applications of thermophils, it is very important to know more about their proteomes and metabolomes. Since thermophils live in stressful environments it will be very useful to study their survival mechanisms. There are many reports on stress induced proteins, particularly the well characterized heat shock proteins, but little is known about the functions of proteins induced after a decrease in temperature. In this study, the proteomes of the thermophilic bacterium after a temperature down shift from 75°C to 45°C for 2h and 5h were investigated. We also compared protein profiles of early and late cold shock processes to that of cells grown at 75°C and identified a set of proteins, some of which are involved in metabolic processes such as fatty acid synthesis, pentose phosphate pathway, aromatic component degradation and signal transduction. Our data showed this organism could be tolerating the stress conditions by changing its metabolism and physiology., (Copyright © 2011 Elsevier B.V. All rights reserved.)

In this study, the cDNA of a new peptide from the venom of the scorpion, Buthotus saulcyi, was cloned and sequenced. It codes for a 64 residues peptide (Bsaul1) which shares high sequence similarity with depressant insect toxins of scorpions. The differences between them mainly appear in the loop1 which connects the beta-strand1 to the alpha-helix and seems to be functionally important in long chain scorpion neurotoxins. This loop is three amino acids longer in Bsaul1 compared to other depressant toxins. A comparative amino acid sequence analysis done on Bsaul1 and some of alpha-, beta-, excitatory and depressant toxins of scorpions showed that Bsaul1 contains all the residues which are highly conserved among long chain scorpion neurotoxins. Structural model of Bsaul1 was generated using Ts1 (a beta-toxin that competes with the depressant insect toxins for binding to Na(+) channels) as template. According to the molecular model of Bsaul1, the folding of the polypeptide chain is being composed of an anti-parallel three-stranded beta-sheet and a stretch of alpha- helix, tightly bound by a set of four disulfide bridges. A striking similarity in the spatial arrangement of some critical residues was shown by superposition of the backbone conformation of Bsaul1 and Ts1.