Oxygen and toxicity inhibition of amino acid biosynthesis

Boehme, D; Vincent, K; Brown, Olen R.

doi:10.1038/262418a0

Cited by 93 publications

(53 citation statements)

References 5 publications

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“…This s4U-independent growth delay may have been mediated by near-UV-induced cellular damage. The initial target of hyperbaric 02 toxicity has been shown to be leucine-isoleucine-valine biosynthesis; i.e., the addition of these amino acids protected E. coli from this stress (5,6). Additionally, oxidizing agents have been shown to induce synthesis of ppGpp, indicating damage to amino acid biosynthesis (4).…”

Section: Resultsmentioning

confidence: 99%

Near-UV stress in Salmonella typhimurium: 4-thiouridine in tRNA, ppGpp, and ApppGpp as components of an adaptive response

1988

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We have examined the role of 4-thiouridine in the responses of Salmonella typhimurium to near-UV irradiation. Mutants lacking 4-thiouridine (nuv) and mutants defective in the synthesis of ppGpp (guanosine 5'-diphosphate-3'-diphosphate) (relA) were found to be sensitive to killing by near-UV. Near-UV induced the synthesis of a set of proteins that were not induced in the nuv mutant. Some of these proteins were identified as oxidative defense proteins, and others were identified as ppGpp-inducible proteins. Over 100-fold increases in ApppGpp (adenosine 5', 5"'-triphosphoguanosine-3"'-diphosphate, the adenylylated form of ppGpp) were observed in wild-type cells after near-UV irradiation but not in the 4-thiouridine-deficient mutant. These data support a model in which ppGpp and ApppGpp, a dinucleotide proposed to be synthesized by tRNA-aminoacyl synthetases as a response to the cross-linking of 4-thiouridine in tRNA by near-UV, induce the synthesis of proteins necessary for resistance to near-UV irradiation.One of the most common stresses confronted by organisms is solar radiation. The most energetic part of the solar spectrum which penetrates the atmosphere is the near-UV region (300 to 400 nm) (22). Studies on the environment mortality of bacteria have found that die-off is dependent on light exposure, especially the near-UV portion of the solar spectrum (10,16,17). Since enteric bacteria such as Escherichia coli must adapt to exposures of near-UV during transmission between hosts (8), they are an ideal system for characterizing mechanisms involved in protection from the toxic effects of near-UV.The irradiation of growing E. coli cells with near-UV results in the cessation of growth long before lethal effects are observed (21,22). This growth lag is dependent on the tRNA-modified base 4-thiouridine (s4U), which is found in 65% of tRNA species (22,40,45). This base is unusual in that it has an absorption maximum in the near-UV region (334 nm). After exposure to near-UV, S4U participates in a photochemical reaction which generates intramolecular cross-linking between S4U and a specific cytosine (13,14,29). These cross-linked tRNAs have been shown to be poor substrates for aminoacylation (51). The accumulation of nonaminoacylated tRNA serves to trigger the stringent response via the relA gene product, which is involved in the synthesis of ppGpp (guanosine 5'-diphosphate-3'-diphosphate) (9, 15), which then acts to inhibit stable RNA synthesis while inducing amino acid biosynthesis (15, 43). Inhibition of protein synthesis after near-UV exposure in E. coli is a result of both the stringent response and decreased aminoacylation of tRNA (44).Near-UV exerts toxic effects on E. coli and Salmonella typhimurium at higher fluences, primarily through oxidative mechanisms (22, 23). Macromolecules which absorb in the near-UV region (i.e., heme and flavins) may act as endogenous photosensitizers, transferring the absorbed energy to 02 and forming toxic oxygen species (10,22,23,48). The response of bacteria to oxidative stress (s...

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Section: Resultsmentioning

confidence: 99%

Near-UV stress in Salmonella typhimurium: 4-thiouridine in tRNA, ppGpp, and ApppGpp as components of an adaptive response

1988

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“…The superoxide anion radical has been reported to damage cell membrane (22) and DNA (35), and to inactivate various enzymes (6). Also, it has been implicated in a variety of pathologic processes, including diabetes mellitus (11), lung damage (20), hepatitis (36), myocardial reperfusion injury following surgery (16), cataract (4), and so on.…”

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confidence: 99%

Immunohistochemical assessment of superoxide dismutase expression in the human endometrium throughout the menstrual cycle.

Narimoto

Noda

Shiotani

et al. 1990

Acta Histochem. Cytochem

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The immunohistochemical distribution of superoxide dismutase (SOD) was examined in the human endometrium throughout the menstrual cycle. Surface and glandular epithelia showed positive staining throughout the menstrual cycle except just prior to the menstruation.Staining activity was more intense in the cytoplasm than that in the nucleus. Specific immunostaining of SOD was demonstrated in sub-and supranuclear vacuoles of glandular epithelia, and intraglandular substances during the early and mid secretory phases; i.e., the preand peri-implantation periods. Meanwhile, stromal cells showed weaker staining activity than surface and glandular epithelia throughout the menstrual cycle until the 22th day. Once the predecidual change occurred in stromal cells on the 23th day, predecidual cells came to show intensive staining. However, specific staining was shown neither in predecidual cells nor in surface or glandular epithelia just prior to the menstruation. In addition, SOD activity was also shown in the decidual cells of 8 weeks gestation and in the reserve cells of the endocervix. Collectively, the present immunohistochemical recults suggest that SOD may play an important role not only in the protection of developing embryos from superoxide anion radicals but also in the local defense mechanism against tissue damages resulting from inflammation in the uterine cavity, and that the expression of SOD may be regulated by sex steroids, especially progestorone. Furthermore, SOD could be a useful indicator to clinically diagnose the degree of predecidualization and the luteal phase defect.The superoxide anion, a free radical generated during the monovalent metabolic reduction of oxygen, is toxic to the aerobic cell in which it is produced (13). The superoxide anion radical has been reported to damage cell membrane (22) and DNA (35), and to inactivate various enzymes (6). Also, it has been implicated in a variety of pathologic processes, including diabetes mellitus (11), lung damage (20), hepatitis (36), myocardial reperfusion injury following surgery (16), cataract (4), and so on. Therefore, effective detoxication of the superoxide anion radical appears to be a prerequisite for life in an oxygen-containing environment. Superoxide dismutase (SOD), known as superoxide oxidoreductase is an enzyme that catalyzes the dismutation (reduction/oxidation) of the superoxide anion radical in the following reaction: 2H+ +202 --k H202+02, and it is important as a biological defense mechanism against 487 488 Narimoto et al.cell injury mediated through superoxide anion radicals (12). In mammalians, three types of SOD have been identified which have different structures and metal contents: a cytoplasmic copper-zinc SOD (CuZn-SOD) (26), a mitochondrial manganese SOD (Mn-SOD) (3) and an extracellular SOD of high molecular weight (EC-SOD) (23).Mammalian preimplantation embryos grown in vitro are likely to exhibit sub-optimal or retarded development (45). In rodents, for example, the 2-cell block phenomenon, i.e., the proliferation arrest of f...

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“…The superoxide anion radical has been reported to damage cell membranes (20) and DNA (30), and to inactivate various enzymes (6) in the aerobic cells in which it is generated during the monovalent metabolic reduction of oxygen. Also, it has been implicated in a variety of pathologic processes (5,10,17,18,31).…”

mentioning

confidence: 99%

Role of superoxide dismutase in the fallopian tube function: Immunohistochemical assessment of superoxide dismutase in the fallopian tube.

Narimoto

Noda

Shiotani

et al. 1991

Acta Histochem. Cytochem

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Oxygen and toxicity inhibition of amino acid biosynthesis

Cited by 93 publications

References 5 publications

Near-UV stress in Salmonella typhimurium: 4-thiouridine in tRNA, ppGpp, and ApppGpp as components of an adaptive response

Near-UV stress in Salmonella typhimurium: 4-thiouridine in tRNA, ppGpp, and ApppGpp as components of an adaptive response

Immunohistochemical assessment of superoxide dismutase expression in the human endometrium throughout the menstrual cycle.

Role of superoxide dismutase in the fallopian tube function: Immunohistochemical assessment of superoxide dismutase in the fallopian tube.

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