A randomised investigation of journal responses to academic and journalist enquiry about possible scientific misconduct.

OBJECTIVE: We investigated whether responses about possible scientific misconduct from journals to journalists would differ in speed, usefulness, and tone from responses to academics. Twelve journals that published 23 clinical trials about which concerns had been previously raised were randomly assigned to enquiries by a journalist or academics. Emails were sent every 3 weeks to the journal editor. We recorded the time for the journal to respond, and two investigators independently assessed the usefulness and tone of the journal responses. RESULTS: 10/12 journals responded: 3 after one email, 5 after two emails, and 2 after three emails (median time from first email to response: 21 days; no difference in response times to journalist or academics, P = 0.25). Of the 10 responses, 8 indicated the journal was investigating, 5 had a positive tone, 4 a neutral tone, and 1 a negative tone. Five of the enquiries by the academics produced information of limited use and 1 no useful information, whereas none of the 6 journalist enquiries produced useful information (P = 0.015). None of the 10 responses was considered very useful. In conclusion, journal responses to a journalist were less useful than those to academics in understanding the status or outcomes of journal investigations.

Mitochondria mediate septin cage assembly to promote autophagy of Shigella.

Septins, cytoskeletal proteins with well-characterised roles in cytokinesis, form cage-like structures around cytosolic Shigella flexneri and promote their targeting to autophagosomes. However, the processes underlying septin cage assembly, and whether they influence S. flexneri proliferation, remain to be established. Using single-cell analysis, we show that the septin cages inhibit S. flexneri proliferation. To study mechanisms of septin cage assembly, we used proteomics and found mitochondrial proteins associate with septins in S. flexneri-infected cells. Strikingly, mitochondria associated with S. flexneri promote septin assembly into cages that entrap bacteria for autophagy. We demonstrate that the cytosolic GTPase dynamin-related protein 1 (Drp1) interacts with septins to enhance mitochondrial fission. To avoid autophagy, actin-polymerising Shigella fragment mitochondria to escape from septin caging. Our results demonstrate a role for mitochondria in anti-Shigella autophagy and uncover a fundamental link between septin assembly and mitochondria.

Loss of elongation factor P disrupts bacterial outer membrane integrity.

Elongation factor P (EF-P) is posttranslationally modified at a conserved lysyl residue by the coordinated action of two enzymes, PoxA and YjeK. We have previously established the importance of this modification in Salmonella stress resistance. Here we report that, like poxA and yjeK mutants, Salmonella strains lacking EF-P display increased susceptibility to hypoosmotic conditions, antibiotics, and detergents and enhanced resistance to the compound S-nitrosoglutathione. The susceptibility phenotypes are largely explained by the enhanced membrane permeability of the efp mutant, which exhibits increased uptake of the hydrophobic dye 1-N-phenylnaphthylamine (NPN). Analysis of the membrane proteomes of wild-type and efp mutant Salmonella strains reveals few changes, including the prominent overexpression of a single porin, KdgM, in the efp mutant outer membrane. Removal of KdgM in the efp mutant background ameliorates the detergent, antibiotic, and osmosensitivity phenotypes and restores wild-type permeability to NPN. Our data support a role for EF-P in the translational regulation of a limited number of proteins that, when perturbed, renders the cell susceptible to stress by the adventitious overexpression of an outer membrane porin.