## 1 Introduction  
Over countless centuries, several organisms have mastered the art of surviving a wide array of adverse conditions (also known as stressors) such as temperature, pH, radiation, salinity, toxic chemicals, nutrients, and low oxygen levels, which are able to modify the homeostasis and status of cells [1]. The adaptation and survival of various organisms under stressful conditions over part of their success either to the augmentation of regulatory and protective stress resistance mechanisms or to the down-regulation of nonstress genes. Among the former exists an enigmatic family of proteins, known as universal stress proteins (USPs). They are recognized as a conserved family known as the universal stress protein A (Pfam classification PF00582) orthologous superfamily (COG0589) [2]. Their name describes the nature of their function; these proteins are involved in cellular responses to abiotic and biotic stresses alike that include, but are not limited to, heat shock, acid and/or high salinity environments, the presence of oxidants, DNA damaging agents, macromolecular damage, nutrient starvation, uncouplers, and pH and antibiotic stress, while they physiologically function in cell growth and development regulation, ion scavenging, cellular mobility and hypoxia responses [2, 3, 4, 5, 6]. The universal stress protein, first known as C13.5, was discovered more than 25 years ago in _E. coli_ as a characteristic 13.5 kDa cytoplasmic protein that appeared as a unique spot on a two-dimensional isoelectric focusing PAGE-gel system by [PERSON] and [PERSON] in response to some of the above-mentioned stresses, apart from cold shock and the tetracycline antibiotic, which failed to elicit the response [7, 8]. At the time, several global regulators were under study and it was known that most proteins encoded by stress or starvation stimulons were generally induced by a specific stimulus although stimulons could share member proteins. UspA was unique because it was a universal non-specific responder to various stimuli. Subsequent studies suggested that UspA plays a role in both protection and regulation as it pertains to growth arrest due to UspA-deficient _E. coli_ strains that struggled to survive extended periods of growth inhibition triggered by several stressors [9]. Other studies suggested that the production of UspA was more growth phase related than growth-rate dependent because growth-arrested cells focus more on maintaining their current state, using the resources that remain after depletion rather than on proliferation and growth [10; 11]. The importance of this protein for cell survival was demonstrated in several ways: (1) production of mutant _E. coli_ cells lacking UspA show increased susceptibility to death or impairment when exposed to complete and prolonged growth inhibition stresses such as extended carbon starvation, H2O2, carbonyl cyanide chlorophenylhydrazone, cadmium chloride and dinitrophenol exposure, as well as osmotic shock; (2) the over-expression of UspA results in the blockage of growth-arrested cells; and (3) mutations in the _uspA_ gene exert an effect on gene expression timing, which in turn accelerates gene expression pattern changes and protein synthesis [9; 12; 13]. Transcription of the _uspA_ gene is a result of a \(\sigma\)70-dependent promoter, which is turned off rapidly once a nutritional up-shift is observed in growth-arrested bacteria [13; 14]. The fact that the gene is incorporated in the FadR regulon suggests its potential role in fatty acid or membrane lipid metabolism, since FadR represses and activates genes involved in fatty acid degradation and biosynthesis respectively [7; 10]. Positive regulation of the _uspA_ gene occurs via alarmone guanosine tetraphosphate or ppGpp, a key nucleotide that regulates numerous stationary phase-induced genes, which it does through the \(\beta\)-subunit of RNA polymerase [7; 11].