Mostly Microbes and Infection - by David Ojcius

Cryo‑electron tomography of Mycoplasma pneumoniae reveals a surface complex combining the conserved Sec‑translocon with a dome‑like assembly formed by three previously uncharacterized Mdps. Integrative proteomics and structural modeling show Mdps resemble PrsA‑like foldases, with Mdp444 retaining catalytic activity. The study provides sub‑nanometer maps of SecA‑mediated translocation coordinated with extracellular protein folding.

Migratory locust eggs emit the microbial volatile 2,4,6‑trimethylpyridine, attracting conspecific females through LmOR34 and LmOR36 to synchronize oviposition. The compound is produced by Enterobacter roggenkampii via lysine degradation, and its loss disrupts attraction. Beyond coordination, 2,4,6‑trimethylpyridine repels soil predators, revealing a dual reproductive and defensive signaling system.

Clostridium immunis protects mice from obesity by secreting a phosphocholine‑modified exopolysaccharide that lowers IL‑22 in the intestine and visceral fat, boosting metabolic activity in adipose tissue. Mutant studies show phosphocholine is essential. Humans with obesity show reduced phosphocholine‑gene abundance, highlighting a translatable strategy to reduce visceral fat.

Analysis of 507 gastric biopsies from 193 children revealed diverse microbial signatures, with HHV6/HHV7 frequently detected and EBV present in a consistent subset. H. pylori showed the strongest link to moderate‑to‑severe inflammation, while EBV also correlated with inflammation, including in H. pylori‑negative patients, highlighting complex pediatric gastric microbial interactions.

The Mononuclear Phagocyte System spans the body and supports homeostasis through highly adaptable interactions beyond immunity. This article introduces a special issue reviewing key phagocyte populations across major organ systems, highlighting their physiologic roles comparable to neuro‑endocrine networks and offering guidance for further study.

First‑line fecal microbiota transplantation yields rapid improvement in most patients with immune checkpoint inhibitor–mediated colitis. In this cohort, 76.9% responded within a median 1.5 days, with increased microbial diversity and reduced immune‑cell activation after treatment. Multi‑omics profiling highlights potential mechanisms underlying FMT response.