We have cloned a regulatory gene for amylase synthesis in Aspergillus oryzae. This gene, amyR, encodes a 604-amino acid transcriptional activator with a Cys6 zinc cluster, that shows extensive homology to the DNA binding domain of GAL4 from Saccharomyces cerevisiae. The DNA binding domain of amyR binds to two types of sequences found in a number of promoters from Aspergillus genes coding for starch-degrading enzymes. One type of binding site is characterized by two CGG triplets separated by eight nucleotides. The other type has only one CGG triplet, which is followed by the sequence AAATTTAA.
SummaryThe predisposition of preterm neonates to invasive infection is, as yet, incompletely understood. Regulatory T cells (T regs ) are potential candidates for the ontogenetic control of immune activation and tissue damage in preterm infants. It was the aim of our study to characterize lymphocyte subsets and in particular CD41 CD25 1 forkhead box protein 3 (FoxP3) 1 T regs in peripheral blood of well-phenotyped preterm infants (n 5 117; 23 1 0 -36 1 6 weeks of gestational age) in the first 3 days of life in comparison to term infants and adults. We demonstrated a negative correlation of T reg frequencies and gestational age. T regs were increased in blood samples of preterm infants compared to term infants and adults. Notably, we found an increased T reg frequency in preterm infants with clinical early-onset sepsis while cause of preterm delivery, e.g. chorioamnionitis, did not affect T reg frequencies. Our data suggest that T regs apparently play an important role in maintaining maternal-fetal tolerance, which turns into an increased sepsis risk after preterm delivery. Functional analyses are needed in order to elucidate whether T regs have potential as future target for diagnostics and therapeutics.
dBurkholderia glumae PG1 is a soil-associated motile plant-pathogenic bacterium possessing a cell density-dependent regulation system called quorum sensing (QS). Its genome contains three genes, here designated bgaI1 to bgaI3, encoding distinct autoinducer-1 (AI-1) synthases, which are capable of synthesizing QS signaling molecules. Here, we report on the construction of B. glumae PG1 ⌬bgaI1, ⌬bgaI2, and ⌬bgaI3 mutants, their phenotypic characterization, and genome-wide transcriptome analysis using RNA sequencing (RNA-seq) technology. Knockout of each of these bgaI genes resulted in strongly decreased motility, reduced extracellular lipase activity, a reduced ability to cause plant tissue maceration, and decreased pathogenicity. RNA-seq analysis of all three B. glumae PG1 AI-1 synthase mutants performed in the transition from exponential to stationary growth phase revealed differential expression of a significant number of predicted genes. In comparison with the levels of gene expression by wild-type strain B. glumae PG1, 481 genes were differentially expressed in the ⌬bgaI1 mutant, 213 were differentially expressed in the ⌬bgaI2 mutant, and 367 were differentially expressed in the ⌬bgaI3 mutant. Interestingly, only a minor set of 78 genes was coregulated in all three mutants. The majority of the QS-regulated genes were linked to metabolic activities, and the most pronounced regulation was observed for genes involved in rhamnolipid and Flp pilus biosynthesis and the type VI secretion system and genes linked to a clustered regularly interspaced short palindromic repeat (CRISPR)-cas gene cluster. Q uorum sensing (QS) is a cell density-dependent gene regulation system in bacteria (1) in which the population density is sensed through the accumulation of bacterially produced signaling molecules called autoinducers (AIs). This cell-to-cell signaling process allows the microbial population to synchronize group behavior and alter its gene expression accordingly. QS is involved in a wide array of regulatory circuits, among which are pathogenicity, secretion of extracellular proteins, secondary metabolite production, and others (2). Key QS signaling molecules in many Gram-negative bacteria are N-acyl-homoserine lactones (AHLs) (3-5), synthesized mainly through LuxI homologs (EC 2.3.1.184) using S-adenosylmethionine (SAM), and an acyl-acyl carrier protein (acyl-ACP) from the fatty acid biosynthesis pathway (6). LuxR-type receptor/regulator proteins are involved in AHL signal perception. Together with LuxR, other proteins may be part of this regulatory circuit.The motile, rod-shaped Gram-negative soil bacterium Burkholderia glumae is considered to be a seed-borne pathogen that causes panicle blight of rice (7). B. glumae has also been reported to infect other plant species, like tomato, sunflower, and pepper (8, 9). Although it is not classified as a human pathogen, a single case of the isolation of B. glumae from a clinical sample was reported (10), indicating that at least some strains of this pathogen may be associated w...
Plant-released flavonoids induce the transcription of symbiotic genes in rhizobia and one of the first bacterial responses is the synthesis of so called Nod factors. They are responsible for the initial root hair curling during onset of root nodule development. This signal exchange is believed to be essential for initiating the plant symbiosis with rhizobia affiliated with the Alphaproteobacteria. Here, we provide evidence that in the broad host range strain Sinorhizobium fredii NGR234 the complete lack of quorum sensing molecules results in an elevated copy number of its symbiotic plasmid (pNGR234a). This in turn triggers the expression of symbiotic genes and the production of Nod factors in the absence of plant signals. Therefore, increasing the copy number of specific plasmids could be a widespread mechanism of specialized bacterial populations to bridge gaps in signaling cascades.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.