Transcription of specific genes in bacteria under environmental stress is frequently initiated by extracytoplasmic function (ECF) σ factors. ECFs σ factors harbour two conserved domains, σ and σ, for transcription initiation by recognition of the promoter region and recruitment of RNA polymerase (RNAP). The crystal structure of Streptomyces tsukubaensis SigG1, an ECF56-family σ factor, was determined revealing σ, σ and the additional carboxi-terminal domain SnoaL_2 tightly packed in a compact conformation.
View Article and Find Full Text PDFIntracellular heme formation and trafficking are fundamental processes in living organisms. Bacteria and archaea utilize three biogenesis pathways to produce iron protoporphyrin IX (heme ) that diverge after the formation of the common intermediate uroporphyrinogen III (uro'gen III). In this study, we identify and provide a detailed characterization of the enzymes involved in the transformation of uro'gen III into heme in , demonstrating that this bacterium utilizes the protoporphyrin-dependent (PPD) pathway.
View Article and Find Full Text PDFThe has developed a consortium of enzymes capable of overcoming steric constraints and degrading, in a sequential manner, the complex rhamnogalacturonan II (RG-II) polysaccharide. BT0996 protein acts in the initial stages of the RG-II depolymerisation, where its two catalytic modules remove the terminal monosaccharides from RG-II side chains A and B. BT0996 is modular and has three putative carbohydrate-binding modules (CBMs) for which the roles in the RG-II degradation are unknown.
View Article and Find Full Text PDFIndividuals learn which of their actions are likely to be rewarded through trial and error. This form of learning is critical for adapting to new situations, which adolescents frequently encounter. Adolescents are also greatly influenced by their peers.
View Article and Find Full Text PDFCogn Affect Behav Neurosci
June 2015
Throughout our lives, we face the important task of distinguishing rewarding actions from those that are best avoided. Importantly, there are multiple means by which we acquire this information. Through trial and error, we use experiential feedback to evaluate our actions.
View Article and Find Full Text PDFNeurosci Biobehav Rev
November 2013
Plasticity refers to changes in the brain that enable an organism to adapt its behavior in the face of changing environmental demands. The evolutionary role of plasticity is to provide the cognitive flexibility to learn from experiences, to monitor the world based on learned predictions, and adjust actions when these predictions are violated. Both progressive (myelination) and regressive (synaptic pruning) brain changes support this type of adaptation.
View Article and Find Full Text PDFPrenatal cocaine exposure leads to persistent alterations in the growth factor brain-derived neurotrophic factor (BDNF), particularly in the medial prefrontal cortex (mPFC) and hippocampus, brain regions important in cognitive functioning. BDNF plays an important role in the strengthening of existing synaptic connections as well as in the formation of new contacts during learning. A single nucleotide polymorphism in the BDNF gene (Val66Met), leading to a Met substitution for Val at codon 66 in the prodomain, is common in human populations, with an allele frequency of 20-30% in Caucasians.
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