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The universal stress protein (USP) domain is a superfamily of conserved genes which can be found in bacteria, archaea, fungi, protozoa and plants.〔.〕 Proteins containing the domain are induced by a plethora of environmental stressors. These conditions include nutrient starvation, drought, extreme temperatures, high salinity, and the presence of uncouplers, antibiotics and metals.〔 In the presence of these stressors, ''Usp'' genes are upregulated resulting in large quantities of their subsequent proteins being produced throughout the cell. The over production of USP domain containing genes allows the organisms to better cope with a varied range of environmental stresses via the action of a number of largely unknown mechanisms. Once stimulated, the USPs will alter the expression of a variety of different genes involved in many different cellular processes. The end result is increased resistance to the stressful condition making this a type of biological defence mechanism. Organisms have many thousands of copies of USP domains within as many genes. However, it is not often known in detail the differences in mechanisms of induction or protection.〔.〕 ==Function== The primary function of this superfamily of genetic domains is to protect the organism during times of environmental stress. Environmental stress, as previously explained, comes in a number of forms. Exposure to a harmful substance or condition, such as UV light, may induce genes containing the USP domain in order to protect the DNA and more generally the cell from further damage.〔 A key example can be found during periods of starvation. In these instances, the USP genes upregulated will often arrest cell growth and in the case of some bacteria, promote a shift to differential metabolic mechanisms which are favourable in conditions of sparse nutrients.〔 Recent research also suggests proteins containing this domain have functions beyond the realms of dealing with environmental stresses.〔.〕 Nachin et al. demonstrated in ''Escherichia coli'' that USPs are involved in actions such as adhesion and motility. The researchers, through means of "knocking out" USP genes known as ''UspE'' and ''UspC'', saw results suggesting an inability to swim and completely lack of motility, respectively. Conversely, mutants for genes ''UspF'' and ''UspG'' were shown to have enhanced swimming abilities. Therefore, mobility is affected both positively and negatively USPs within ''E. coli''. This demonstrates USPs influence throughout the cell could be widespread for a number of reasons. Additionally, in ''Halmonas elongate'', there is a USP called TeaD has been described as a key regulator in the transport of Ectoine across the cell membrane.〔.〕 This demonstrates how versatile USPs can be. Their function, while primarily encompasses increasing survival during stressful conditions, is not always limited to this. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Universal stress protein」の詳細全文を読む スポンサード リンク
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