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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Growth-limiting stresses in bacteria induce the general stress response to protect the cells against future stresses. Energy stress caused by starvation conditions in Bacillus subtilis is transmitted to the sigma(B) transcription factor by stress-response regulators. RsbP, a positive regulator, is a phosphatase containing a PAS (Per-ARNT-Sim) domain and requires catalytic function of a putative alpha/beta hydrolase, RsbQ, to be activated. These two proteins have been found to interact with each other. We determined the crystal structures of RsbQ in native and inhibitor-bound forms to investigate why RsbP requires RsbQ. These structures confirm that RsbQ belongs to the alpha/beta hydrolase superfamily. Since the catalytic triad is buried inside the molecule due to the closed conformation, the active site is constructed as a hydrophobic cavity that is nearly isolated from the solvent. This suggests that RsbQ has specificity for a hydrophobic small compound rather than a macromolecule such as RsbP. Moreover, structural comparison with other alpha/beta hydrolases demonstrates that a unique loop region of RsbQ is a likely candidate for the interaction site with RsbP, and the interaction might be responsible for product release by operating the hydrophobic gate equipped between the cavity and the solvent. Our results support the possibility that RsbQ provides a cofactor molecule for the mature functionality of RsbP.
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PMID:Crystal structures of RsbQ, a stress-response regulator in Bacillus subtilis. 1563 89

The fruit fly Drosophila melanogaster, a widely utilized genetic model, is highly resistant to oxygen starvation and is beginning to be used for studying physiological, developmental, and cellular adaptations to hypoxia. The Drosophila respiratory (tracheal) system has features in common with the mammalian circulatory system so that an angiogenesis-like response occurs upon exposure of Drosophila larvae to hypoxia. A hypoxia-responsive system homologous to mammalian hypoxia-inducible factor (HIF) has been described in the fruit fly, where Fatiga is a Drosophila oxygen-dependent HIF prolyl hydroxylase, and the basic helix-loop-helix Per/ARNT/Sim (bHLH-PAS) proteins Sima and Tango are, respectively, the Drosophila homologues of mammalian HIF-alpha (alpha) and HIF-beta (beta). Tango is constitutively expressed regardless of oxygen tension and, like in mammalian cells, Sima is controlled at the level of protein degradation and subcellular localization. Sima is critically required for development in hypoxia, but, unlike mammalian model systems, it is dispensable for development in normoxia. In contrast, fatiga mutant alleles are all lethal; however, strikingly, viability to adulthood is restored in fatiga sima double mutants, although these double mutants are not entirely normal, suggesting that Fatiga has Sima-independent functions in fly development. Studies in cell culture and in vivo have revealed that Sima is activated by the insulin receptor (InR) and target-of-rapamycin (TOR) pathways. Paradoxically, Sima is a negative regulator of growth. This suggests that Sima is engaged in a negative feedback loop that limits growth upon stimulation of InR/TOR pathways.
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PMID:Cellular and developmental adaptations to hypoxia: a Drosophila perspective. 1799 52

RsbP, a regulator of RNA polymerase sigma(B) activity in Bacillus subtilis, is a phosphatase containing a Per-Arnt-Sim (PAS) domain in its N-terminal region that is expected to sense energy stresses such as carbon, phosphate or oxygen starvation. Energy-stress signals are transmitted to the PAS domain and activate the C-terminal phosphatase domain of RsbP, leading to activation of the downstream anti-anti-sigma(B) factor RsbV. Finally, the general stress response is induced to protect the cells against further stresses. The recombinant PAS domain of RsbP was crystallized by the sitting-drop vapour-diffusion technique using 40% PEG 400 as a precipitant. The crystals belonged to space group P2(1), with unit-cell parameters a = 55.2, b = 71.7, c = 60.2 A, beta = 92.1 degrees . Diffraction data were collected to a resolution of 1.6 A.
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PMID:Expression, crystallization and preliminary crystallographic analysis of the PAS domain of RsbP, a stress-response phosphatase from Bacillus subtilis. 1947 30

The sigma(B)-dependent general stress response in the common soil bacterium Bacillus subtilis can be elicited by a range of stress factors, such as starvation or an ethanol, salt, or heat shock, via a complex upstream signaling cascade. Additionally, sigma(B) can be activated by blue light via the phototropin homologue YtvA, a component of the environmental branch of the signaling cascade. Here we use a reporter-gene fusion to show that sigma(B) can also be activated by red light via the energy branch of its upstream signaling cascade. Deletion mutagenesis and homologous overproduction experiments indicate that the RsbP protein (composed of an N-terminal Per-ARNT-Sim [PAS] domain and a C-terminal PP2C-type phosphatase domain) is involved in the red light response. This second light input pathway functions complementarily to YtvA; it shows broader spectral sensitivity but requires higher light intensities. These results are confirmed by transcriptome analyses, which show that both light effects result in upregulation of the sigma(B) regulon, with minimal activation of other responses.
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PMID:Red light activates the sigmaB-mediated general stress response of Bacillus subtilis via the energy branch of the upstream signaling cascade. 1994 97

Bacterial cell wall homeostasis is an intricately coordinated process that ensures that envelope integrity is maintained during cell growth and division, but can also adequately respond to growth-limiting conditions such as phosphate starvation. In Bacillus subtilis, biosynthesis of the two major cell wall components, peptidoglycan and anionic polymers, is controlled by a pair of paralogous two-component systems, WalRK and PhoPR respectively. Favorable growth conditions allow for a fast rate of cell wall biosynthesis (WalRK-ON) and the incorporation of the phosphate-containing anionic polymer teichoic acids (PhoPR-OFF). In contrast, growth-restricted cells under phosphate-limiting conditions reduce the incorporation of peptidoglycan building blocks (WalRK-OFF) and switch from the phosphate-containing teichoic acids to the phosphate-free anionic polymer teichuronic acid (PhoPR-ON). Botella et al. (2014) deepen our knowledge on the PhoPR system by identifying one signal that is perceived by its histidine kinase PhoR. In fast-growing cells, intracellular intermediates of teichoic acid biosynthesis are sensed by the cytoplasmic Per-Arnt-Sim domain as an indicator of favorable conditions, thereby inhibiting the autokinase activity of PhoR and keeping the system inactive. Depletion of teichoic acid building blocks under phosphate-limiting conditions relieves this inhibition, activates PhoPR-dependent signal transduction and hence the switch to teichuronic acid biosynthesis.
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PMID:A balancing act times two: sensing and regulating cell envelope homeostasis in Bacillus subtilis. 2531 93