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Replacement of the native promoter of theglobal regulator LaeA-like gene of Daldinia eschscholzii by a strong gpdA promoter led to the generation of two novel cyclopentenone metabolites, named dalestones A and B, whose structures were assigned by a combination of spectroscopic analysis, modified Mosher's reaction, and electronic circular dichroism (ECD). Dalestones A and B inhibit the gene expression of TNF- α and IL-6 in LPS-induced RAW264.7 macrophages. [ABSTRACT FROM AUTHOR]

To construct a prototrophic Corynebacterium glutamicum strain that efficiently produces pyruvate from glucose, the effects of inactivating RamA, a global regulator responsible for activating the oxidative tricarboxylic acid (TCA) cycle, on glucose metabolism were investigated. ΔramA showed an increased specific glucose consumption rate, decreased growth, comparable pyruvate production, higher formation of lactate and acetate, and lower accumulation of succinate and 2-oxoglutarate compared to the wild type. A significant decrease in pyruvate dehydrogenase complex activity was observed for ΔramA, indicating reduced carbon flow to the TCA cycle in ΔramA. To create an efficient pyruvate producer, the ramA gene was deleted in a strain lacking the genes involved in all known lactate- and acetate-producing pathways. The resulting mutant produced 161 mM pyruvate from 222 mM glucose, which was significantly higher than that of the parent (89.3 mM; 1.80-fold). [ABSTRACT FROM AUTHOR]

Cronobacter sakazakii is a Gram-negative opportunistic pathogen that causes necrotizing enterocolitis, sepsis, and meningitis in premature infants. The genetic basis of C. sakazakii virulence is poorly understood. In this study, the putative LysR-type transcriptional regulator (LTTR) gene (ESA_01081 homolog) was characterized as a possible regulator for C. sakazakii pathogenesis. An in-frame deletion mutant of the ESA_01081 homolog and its cognate complementation strain were constructed and characterized for pathogenesis (adhesion/invasion potentials to human intestinal cells and in vivo rat pup challenge assay), biofilm formation, resistance to oxidative stress and induction of IL-8 secretion. LTTR-deficient C. sakazakii ATCC 29544 exhibits significantly attenuated phenotypes in all the properties tested, except adhesion. Our data strongly suggest that the putative gpESA_01081 homolog, plays an important regulatory role in diverse biological processes including the virulence of C. sakazakii. This is the first report of a functional global regulator in C. sakazakii. [ABSTRACT FROM AUTHOR]