Volume 3 Issue 12, December 2018

Bacteria employ a specialized weapon known as the type VI secretion system to defend themselves from competing organisms. A new study reveals the molecular architecture of the type VI secretion system and highlights conserved mechanistic similarities with contractile phage tails.

Gut microbiota are known to produce an intermediate metabolite in the production of trimethylamine N-oxide that promotes atherosclerosis. Now, another metabolite produced by the same bacteria has been identified that prevents atherosclerosis. The basis for these opposing microbial effects are dictated by diet.

It is now clear that key autophagy proteins possess alternative functions, distinct from their conventional roles in autophagy. Adding to this emerging field, a new study shows how ATG16L1 acts to promote plasma membrane repair following damage by pore-forming bacteria.

Primate immunodeficiency virus accessory proteins Vpx/Vpr associate with and induce proteasomal degradation of the HUSH complex, thereby counteracting HUSH-mediated epigenetic transcriptional repression of proviral and cellular genes. These findings open new therapeutic avenues against HIV.

The effects of multidrug antimicrobial combinations follow a null model in which inhibitory effects are additive and where drug dosage is orthogonal, leading to a square-root scaling of potency with the number of drugs.

During hypoxic growth in the gut, the levels of nitrate and nitrite affect V. cholerae in a pH-dependent manner. At high pH, the bacteria can reduce nitrate for growth, whereas at low pH, nitrite accumulates, limits proliferation and promotes cell viability.

The human silencing hub (HUSH) complex represses primate immunodeficiency virus transcription and can be counteracted through degradation mediated by viral Vpx or Vpr proteins.

The crystal structure of the PapC usher, together with the PapDG chaperone–subunit complex, helps to elucidate the molecular mechanisms by which individual pilus subunits are assembled into larger P pili.

The interferon-inducible short isoform of human nuclear receptor coactivator 7 (NCOA7) inhibits influenza virus entry into the cytoplasm by interacting with and stimulating the activity of the vacuolar H⁺-ATPase, which leads to inhibition of viral and endosomal membrane fusion.

Chlamydia trachomatis DUB1 uses a single catalytic centre to carry out dual lysine deubiquitinase and acetyltransferase activity. Deubiquitination is required for Golgi fragmentation during bacterial infection.

Although essential to restrict systemic replication, the small interfering RNA pathway fails to efficiently silence dengue virus in the midgut of Aedes aegypti in the absence of ectopic expression of the double-stranded RNA-binding protein Loqs2.

Viral oral infections in Drosophila are cleared independently of the RNAi pathway and confer protection to future reinfections by the same virus.

The cryo-EM structure of the TssKFGE baseplate wedge complex of the type VI secretion system (T6SS) from enteroaggregative Escherichia coli helps to elucidate the molecular architecture of the whole T6SS baseplate, and its assembly and mode of action.

Single-cell genome sequencing of eight uncultured fungal species provides insights into the phylogenetic placement of early-diverging lineages, highlights metabolic deficiencies and identifies gene expansions correlated with parasitism and unculturability.

A combination of cryo-electron microscopy (cryo-EM) and targeted mutagenesis studies elucidates the structure and organization of the core complex of the type IV secretion system used by Xanthomonas citri to kill competing bacteria.

Faecal carbon:nitrogen measurements and manipulation of nitrogen availability via diet and host secretions in a murine model suggest that intestinal nitrogen limitation occurs due to host absorption and microbial use, leading to benefits for specific taxa.

Bacillus subtilis mutants lacking either of the biofilm extracellular matrix components, exopolysaccharide or the fibre protein TasA, can evolve compensatory mutations that act on the residual matrix component to restore biofilm formation.

Roseburia intestinalis is a butyrate-producing member of the gut microbiome that can use dietary plant polysaccharides to alter host metabolism, transcription and epigenetics, and lower inflammation and endotoxaemia, resulting in reduced atherosclerosis.

Autophagy-related proteins ATG16L1, ATG5 and ATG12 are required for plasma membrane repair and help to restrict Listeria monocytogenes toxin-mediated cell-to-cell spread.