Emergent resistance to all clinical antibiotics calls for the next generation of therapeutics. Here we report an effective antimicrobial strategy targeting the bacterial hydrogen sulfide (H2S)–mediated defense system. We identified cystathionine γ-lyase (CSE) as the primary generator of H2S in two major human pathogens, Staphylococcus aureus and Pseudomonas aeruginosa, and discovered small molecules that inhibit bacterial CSE. These inhibitors potentiate bactericidal antibiotics against both pathogens in vitro and in mouse models of infection. CSE inhibitors also suppress bacterial tolerance, disrupting biofilm formation and substantially reducing the number of persister bacteria that survive antibiotic treatment. Our results establish bacterial H2S as a multifunctional defense factor and CSE as a drug target for versatile antibiotic enhancers.

A high-sugar diet has been associated with reduced lifespan in organisms ranging from worms to mammals. However, the mechanisms underlying the harmful effects of glucose are poorly understood. Here we establish a causative relationship between endogenous glucose storage in the form of glycogen, resistance to oxidative stress and organismal aging in Caenorhabditis elegans. We find that glycogen accumulated on high dietary glucose limits C. elegans longevity. Glucose released from glycogen and used for NADPH/glutathione reduction renders nematodes and human hepatocytes more resistant against oxidative stress. Exposure to low levels of oxidants or genetic inhibition of glycogen synthase depletes glycogen stores and extends the lifespan of animals fed a high glucose diet in an AMPK-dependent manner. Moreover, glycogen interferes with low insulin signalling and accelerates aging of long-lived daf-2 worms fed a high glucose diet. Considering its extensive evolutionary conservation, our results suggest that glycogen metabolism might also have a role in mammalian aging.

Translation elongation factor eEF1A has a well-defined role in protein synthesis. In this study, we demonstrate a new role for eEF1A: it participates in the entire process of the heat shock response (HSR) in mammalian cells from transcription through translation. Upon stress, isoform 1 of eEF1A rapidly activates transcription of HSP70 by recruiting the master regulator HSF1 to its promoter. eEF1A1 then associates with elongating RNA polymerase II and the 3′UTR of HSP70 mRNA, stabilizing it and facilitating its transport from the nucleus to active ribosomes. eEF1A1-depleted cells exhibit severely impaired HSR and compromised thermotolerance. In contrast, tissue-specific isoform 2 of eEF1A does not support HSR. By adjusting transcriptional yield to translational needs, eEF1A1 renders HSR rapid, robust, and highly selective; thus, representing an attractive therapeutic target for numerous conditions associated with disrupted protein homeostasis, ranging from neurodegeneration to cancer.DOI: http://dx.doi.org/10.7554/eLife.03164.001

Psu, a coat protein from bacteriophage P4, has been shown to inhibit Rho-dependent transcription termination in vivo. Cooverexpression of Psu and Rho led to the loss of viability of the cells, which is the consequence of the anti-Rho activity of the protein. The antitermination property of Psu is abolished either by the deletion of 10 or 20 amino acids from its C terminus or by a mutation, Y80C, in Rho. All these experiments indicated probable interactions between Rho and Psu. Purified Psu protein is ␣-helical in nature and appeared to be a dimer. Co-purification of Rho and wild-type Psu on an affinity matrix and co-elution of both of them in Superose-6 gel filtration suggests a direct association of these proteins, whereas a C terminus 10-amino acid deletion derivative of Psu failed to be pulled down in this assay. This indicates that the loss of the function of these mutants is correlated with their inability to interact with each other. In vitro termination assays revealed that Psu can inhibit Rho-dependent termination specifically in a concentration-dependent manner. The presence of Psu affected the affinity of ATP and reduced the rate of ATPase activity of Rho but did not affect either primary or secondary RNA binding activities. In the presence of Psu, Rho was also observed to release RNA very slowly from a stalled elongation complex. We propose that Psu inhibits Rho-dependent termination by slowing down the translocation of Rho along the RNA because of its slow ATPase activity.

Transcription-coupled DNA repair (TCR) acts on lesions in the transcribed strand of active genes. Helix distorting adducts and other forms of DNA damage often interfere with the progression of the transcription apparatus. Prolonged stalling of RNA polymerase can promote genome instability and also induce cell cycle arrest and apoptosis. These generally unfavorable events are counteracted by RNA polymerase-mediated recruitment of specific proteins to the sites of DNA damage to perform TCR and eventually restore transcription. In this perspective we discuss the decision-making process to employ TCR and we elucidate the intricate biochemical pathways leading to TCR in E. coli and human cells.