The occurrence and ecology of microbial chain elongation of carboxylates in soils

Chain elongation is a growth-dependent anaerobic metabolism that combines acetate and ethanol into butyrate, hexanoate, and octanoate. While the model microorganism for chain elongation, Clostridium kluyveri, was isolated from a saturated soil sample in the 1940s, chain elongation has remained unexplored in soil environments. During soil fermentative events, simple carboxylates and alcohols can transiently accumulate up to low mM concentrations, suggesting in situ possibility of microbial chain elongation. Here, we examined the occurrence and microbial ecology of chain elongation in four soil types in microcosms and enrichments amended with chain elongation substrates. All soils showed evidence of chain elongation activity with several days of incubation at high (100 mM) and environmentally relevant (2.5 mM) concentrations of acetate and ethanol. Three soils showed substantial activity in soil microcosms with high substrate concentrations, converting 58% or more of the added carbon as acetate and ethanol to butyrate, butanol, and hexanoate. Semi-batch enrichment yielded hexanoate and octanoate as the most elongated products and microbial communities predominated by C. kluyveri and other Firmicutes genera not known to undergo chain elongation. Collectively, these results strongly suggest a niche for chain elongation in anaerobic soils that should not be overlooked in soil microbial ecology studies.

Identification of a compound, at a very low dose (less than 100 ng/g of diet), with lifespan-elongation activity towards SOD-1 mutant adults of Drosophila melanogaster in the hot water extract of Chlorella pyrenoidosa

Hot water extract of chlorella (WEC) increased the lifespan of superoxide dismutase (SOD)-1 mutant adults of Drosophila melanogaster in a dose dependent manner (200–800 µg/mL). Compounds in WEC were successively fractionated by solid phase extraction using a Sep-Pak C18 cartridge and size exclusion chromatography (SEC). Amino compounds in SEC fractions were derivatized with 6-aminoquinolyl-N-hydroxylsuccinimidyl carbamate and analyzed by reversed phased-liquid chromatography-tandem mass spectrometry. Phenylalanine, phenethylamine, isopentylamine, and 2-methylbutylamine were identified in the SEC fraction, which increased the lifespan of the D. melanogaster mutant adults. Phenethylamine, at very low doses (6–60 ng/g of diet) that roughly corresponded to those of phenethylamine in WEC (200–800 μg/mL), increased the lifespan of the D. melanogaster adults, while isopentylamine did not exert the lifespan elongation activity. Since phenethylamine did not show SOD-like activity, it did not increase lifespan by direct antioxidant activity.

Inositol pyrophosphates regulate RNA polymerase I-mediated rRNA transcription in Saccharomyces cerevisiae

Inositol pyrophosphates are phosphate-rich metabolic messengers that regulate many cellular processes. We observed that RNA polymerase I is pyrophosphorylated by inositol pyrophosphates, and its transcription elongation activity was reduced in budding yeast strains devoid of inositol pyrophosphates.

Novel Antiviral Agent DTriP-22 Targets RNA-Dependent RNA Polymerase of Enterovirus 71

ABSTRACT Enterovirus 71 (EV71) has emerged as an important virulent neurotropic enterovirus in young children. DTriP-22 (4{4-[(2-bromo-phenyl)-(3-methyl-thiophen-2-yl)-methyl]-piperazin-1-yl}-1-pheny-1H-pyrazolo[3,4-d]pyrimidine) was found to be a novel and potent inhibitor of EV71. The molecular target of this compound was identified by analyzing DTriP-22-resistant viruses. A substitution of lysine for Arg163 in EV71 3D polymerase rendered the virus drug resistant. DTriP-22 exhibited the ability to inhibit viral replication by reducing viral RNA accumulation. The compound suppressed the accumulated levels of both positive- and negative-stranded viral RNA during virus infection. An in vitro polymerase assay indicated that DTriP-22 inhibited the poly(U) elongation activity, but not the VPg uridylylation activity, of EV71 polymerase. These findings demonstrate that the nonnucleoside analogue DTriP-22 acts as a novel inhibitor of EV71 polymerase. DTriP-22 also exhibited a broad spectrum of antiviral activity against other picornaviruses, which highlights its potential in the development of antiviral agents.

Mutational Analysis of an RNA Polymerase II Elongation Factor in Drosophila melanogaster

ABSTRACT The ELL family of proteins function in vitro as elongation factors for RNA polymerase II. Deletion studies have defined domains in mammalian ELL required for transcription elongation activity and RNA polymerase binding in vitro, for transformation of cultured cells when overexpressed, and for leukemogenesis and cell proliferation as part of a leukemic fusion protein. The goal of this study was to identify domains required for chromosome targeting and viability in the unique Drosophila ELL (dELL) protein. Here, we show that an N-terminal domain of dELL is necessary and sufficient for targeting to transcriptionally active puff sites in chromatin, supporting a role for this domain in recruiting dELL to elongating RNA polymerase II. We demonstrate that a central domain of dELL is required for rapid mobilization of ELL during the heat shock response, suggesting a regulatory function for this domain. Unexpectedly, transgenic dELL in which the N-terminal chromosome binding domain is deleted can complement the recessive lethality of mutations in ELL, suggesting that Drosophila ELL has an essential activity in development distinct from its role as an RNA polymerase II elongation factor.