Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This review describes a range of pH responses. Some are only induced if relevant DNA is brought to an appropriately supercoiled configuration by DNA gyrase and bent by the action of, for example, integration host factor (IHF). Bending may allow transcription by bringing activators into juxtaposition with RNA polymerase, which is CysB-associated in several of the responses. Control of arginine decarboxylase (AdiA) synthesis at acid pH is of the above type, with dependence on the presence of gyrase, H-NS, IHF and CysB; acid induction of LysU has similar requirements but also needs Lrp; lysine decarboxylase (CadA) formation at acid pH is controlled quite differently, needing the CadC activator and interaction of lysine/lysine permease; H-NS probably reverses induction by CadC. The Hyd components of formic hydrogenlyase are induced by acid under anaerobiosis; a transcriptional activator is involved and Fur may also function in regulation. Acid tolerance induced at low pH in log-phase cells needs CysB and PhoE but not DNA gyrase; tolerance is reduced by NaCl but not affected by Fe3+, Fe2+, glucose/cAMP or by lrp, him, fur, hns or nhaA/B lesions. Alkali tolerance (habituation), induced at pH0 8.5-9.0, probably involves DNA supercoiling and bending; the induction process needs IHF, CysB, PhoE, NhaA, TonB and Fur and is glucose-repressed; tolerance may result from Na+ efflux catalysed by the NhaA antiporter, which is induced at pH0 9.0. Alkali sensitivity induced at pH0 5.5 also requires gyrase, IHF and CysB, but H-NS, Lrp, NhaA and OmpC are also needed and induction is abolished by NaCl. Salt-induced acid sensitivity results from PhoE formation and is blocked by glucose (reversed by cAMP), FeCl3 and hns and relA lesions, the effect of relA being envZ-suppressed. Acid sensitivity induction (ASI) at pH0 9.0 needs H-NS, is inhibited by FeCl3 and amiloride, and is associated with alkyl hydroperoxide reductase synthesis. Leucine-induced acid sensitivity needs gyrase, CysB, H-NS, Fur, OmpA and RelA, is inhibited by Fe3+, Fe2+, tetracycline, glucose and nalidixic acid, but not by chloramphenicol; increased outer membrane proton passage may result from OmpA modification.
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PMID:Regulatory components, including integration host factor, CysB and H-NS, that influence pH responses in Escherichia coli. 917 36

Salmonella Typhimurium CECT 443 inactivation at pH 2.5 in Mineral Medium (MM) and MM supplemented with 0.01% (w/v) arginine, lysine or glutamic acid was studied using stationary-phase cells grown in buffered BHI pH 7.0 (non-acid adapted cells) and acidified BHI up to pH 4.5 with acetic, citric, lactic and hydrochloric acids (acid adapted cells). In all cases, acid adapted cells, with D-values ranging from 23.34 to 86.90 min, showed a significantly higher acid resistance than non-acid adapted cells, with D-values between 8.90 and 10.29 min. Whereas the conditions used for acid adaptation did not exert a significant effect on the acid resistance of the S. Typhimurium CECT 443 resulting cells, the inclusion of lysine and arginine in the challenge medium protected them against acid inactivation, reaching D-values of about 2 and 3 times higher, respectively, than those found in MM or MM supplemented with glutamic acid. None of these three amino acids significantly modified the acid resistance of non-acid adapted cells. The relative expression level of adiA (encoding the arginine decarboxylase), adiY (encoding the transcriptional activator of adiA), cadA (encoding the lysine decarboxylase) and cadB (encoding the lysine/cadaverine transport protein) was examined by quantitative PCR. Acid adapted cells showed higher relative expression levels for both systems, arginine decarboxylase and lysine decarboxylase, which demonstrates that the induction of specialized pH-homeostatic systems plays an important role in S. Typhimurium CECT 443 protection against acid stress. However, the increased acid resistance showed by acid adapted cells challenged in MM arginine or lysine free suggests the existence of other microbial survival strategies.
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PMID:Arginine and lysine decarboxylases and the acid tolerance response of Salmonella Typhimurium. 1986 32