Two propanediol utilization-like proteins of <Emphasis Type="Italic">Moorella thermoacetica</Emphasis> with phosphotransacetylase activity

Moorella thermoacetica is one of the model acetogenic bacteria for the resolution of the Wood–Ljungdahl (acetyl-CoA) pathway in which CO₂ is autotrophically assimilated yielding acetyl-CoA as central intermediate. Its further conversion into acetate relies on subsequent phosphotransacetylase (PTA) and acetate kinase reactions. However, the genome of M. thermoacetica contains no pta homologous gene. It has been speculated that the moth_0864 and moth_1181 gene products sharing similarities with an evolutionarily distinct phosphotransacylase involved in 1,2-propanediol utilization (PDUL) of Salmonella enterica act as PTAs in M. thermoacetica. Here, we demonstrate specific PTA activities with acetyl-CoA as substrate of 9.05 and 2.03 U/mg for the recombinant enzymes PDUL1 (Moth_1181) and PDUL2 (Moth_0864), respectively. Both showed maximal activity at 65 °C and pH 7.6. Native proteins (90 kDa) are homotetramers composed of four subunits with apparent molecular masses of about 23 kDa. Thus, one or both PDULs of M. thermoacetica might act as PTAs in vivo catalyzing the penultimate step of the Wood–Ljungdahl pathway toward the formation of acetate. In silico analysis underlined that up to now beside of M. thermoacetica, only Sporomusa ovata contains only PDUL like class^III-PTAs but no other phosphotransacetylases or phosphotransbutyrylases (PTBs).     

The effect of intraspecific variation and heritability on community pattern and robustness

Intraspecific trait variation is widespread in nature, yet its effects on community dynamics are not well understood. Here we explore the consequences of intraspecific trait variation for coexistence in two‐ and multispecies competitive communities. For two species, the likelihood of coexistence is in general reduced by intraspecific variation, except when the species have almost equal trait means but different trait variances, such that one is a generalist and the other a specialist consumer. In multispecies communities, the only strong effect of non‐heritable intraspecific variation is to reduce expected species richness. However, when intraspecific variation is heritable, allowing for the possibility of trait evolution, communities are much more resilient against environmental disturbance and exhibit far more predictable trait patterns. Our results are robust to varying model parameters and relaxing model assumptions.     

Organic farming affects the potential of a granivorous carabid beetle to control arable weeds at local and landscape scales

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Strong invaders are strong defenders – implications for the resistance of invaded communities

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The deubiquitinase Usp27x stabilizes the BH3‐only protein Bim and enhances apoptosis

Bim is a pro‐apoptotic Bcl‐2 family member of the BH3‐only protein subgroup. Expression levels of Bim determine apoptosis susceptibility in non‐malignant and in tumour cells. Bim protein expression is downregulated by proteasomal degradation following ERK‐dependent phosphorylation and ubiquitination. Here, we report the identification of a deubiquitinase, Usp27x, that binds Bim upon its ERK‐dependent phosphorylation and can upregulate its expression levels. Overexpression of Usp27x reduces ERK‐dependent Bim ubiquitination, stabilizes phosphorylated Bim, and induces apoptosis in PMA‐stimulated cells, as well as in tumour cells with a constitutively active Raf/ERK pathway. Loss of endogenous Usp27x enhances the Bim‐degrading activity of oncogenic Raf. Overexpression of Usp27x induces low levels of apoptosis in melanoma and non‐small cell lung cancer (NSCLC) cells and substantially enhances apoptosis induced in these cells by the inhibition of ERK signalling. Finally, deletion of Usp27x reduces apoptosis in NSCLC cells treated with an EGFR inhibitor. Thus, Usp27x can trigger via its proteolytic activity the deubiquitination of Bim and enhance its levels, counteracting the anti‐apoptotic effects of ERK activity, and therefore acts as a tumour suppressor.     

Synthesis and evaluation of naphthalene-based thiosemicarbazone derivatives as new anticancer agents against LNCaP prostate cancer cells

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