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Gabriel Waksman found a personal way to overcome his eco-anxiety and combat his carbon emissions — by planting native woodlands.

In this Review, Waksman and colleagues describe the structural and mechanistic details of the six secretion systems (types I–VI) of Gram-negative bacteria, the unique mycobacterial type VII secretion system, the chaperone–usher pathway and the curli biogenesis machinery. They discuss both conserved and divergent properties of these systems and their potential as targets of novel antibacterial compounds.

The crystal structure of the FimD usher traversed by the tip complex of a type 1 pilus demonstrates the mechanism by which pilus subunits are assembled and translocated during pilus elongation.

Chaperone–usher pili are assembled and secreted by a periplasmic chaperone and a dimeric outer-membrane usher complex. Gabriel Waksman and Scott Hultgren review the structural information that has been gathered over the past decade on the various players that participate in P and type 1 pilus biogenesis.

Type IV secretion systems (T4SSs) are found in both Gram-negative and Gram-positive bacteria and generally comprise 12 protein components that are organized into ATP-powered, double-membrane-spanning complexes. Here, Fronzes, Christie and Waksman review the structural data of many T4SS components and propose a model for the assembly of a functional type IV secretion apparatus.

Relaxosome is a complex involved in bacterial conjugation and the spread of antibiotic resistance genes. Using cryo-EM, the authors reveal how specific protein-DNA interactions within the relaxosome facilitate the transfer of plasmid DNA between bacteria.

Type III secretions systems (T3SSs) are major bacterial virulence factors responsible for secretion and injection of protein effectors into host cells. New structures illuminate their ring structure and identify novel ring-mediating structural scaffolds.

Plants frequently face trade-offs of growth and defence. One way for the switch is to produce defensive compounds from primary pathway intermediates. Here, the researchers characterized the biosynthetic pathway of an antibiotic diterpenoid in maize and revealed a crosstalk between maize secondary metabolism and gibberellin biosynthesis.

A membrane-embedded complex (called T4CC) is essential for injection of Legionella pneumophila effector proteins into human macrophages via a Type IV secretion system. Here, the authors purify and study the T4CC using functional and cryo-EM structural analyses, providing insights into the secretion mechanisms.

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.

Pili are crucial virulence factors in many Gram-negative pathogens; these surface structures enable bacteria to interact with, and attach to structures in, their environment and can also facilitate horizontal gene transfer. In this Review, Waksmanet al. examine recent advances in our structural understanding of various pilus systems in Gram-negative bacteria and discuss their functional implications.

Type IV secretion systems span the two membranes of Gram-negative bacteria, with three proteins —— VirB7, VirB9 and VirB10 — assembled into a 1.05 megadalton core spanning the inner and outer membranes. Here, the crystal structure of an outer-membrane complex is presented. The structure is the largest determined for an outer-membrane channel and is unprecedented in being composed of three proteins.

Cryo-electron microscopy structures of a 2.8 megadalton bacterial type IV secretion system encoded by the plasmid R388 and comprising 92 polypeptides provide insights into the stepwise mechanism of pilus assembly.

The bacterial stressosome is a large nanomachine and a key inducer of stress response. Here, the authors present the cryo-EM structure of the stressosome from the bacterial pathogen Listeria monocytogenes at 3.38 Å resolution and discuss its activation mechanism.

Dynamic nuclear polarization–based solid-state nuclear magnetic resonance spectroscopyis applied to study the structure of a large bacterial membrane protein complex in its cellular environment.

Type 1 pili are crucial cell surface bacterial virulence factors. Here, the authors show that FimD is required to assemble the most stable quaternary pilus structure by ensuring that the resulting protein polymer is free of structural defects.

Legionella pneumophila employs the Type 4B secretion system (T4BSS) to translocate more than 300 effector proteins into the host cell during infection. Here the authors present the crystal structure of the DotM soluble domain and give mechanistic insights into the recruitment of Glu-rich motif-containing effectors to the T4BSS.

Reduced glomerular filtration rate (eGFR) is a hallmark of chronic kidney disease. Here, Pattaro et al. conduct a meta-analysis to discover several new loci associated with variation in eGFR and find that genes associated with eGFR loci often encode proteins potentially related to kidney development.

The three-dimensional structure of the type IV secretion system encoded by the Escherichia coli R388 conjugative plasmid.

In this Review, Costa and colleagues summarize the current knowledge of type IV secretion system functioning in Gram-negative bacteria, with a focus on their architectures and adaptations for specialized functions. They also explore the biogenesis pathways and spatial localization of type IV secretion systems.

The translocation assembly module (TAM) of Escherichia coli functions together with the BAM complex to mediate the rapid assembly of usher proteins, the molecular platform important for the biogenesis of bacterial fimbriae.

The Myocardial Infarction Genetics Consortium reports results of a genome-wide association study of early-onset myocardial infarction. The study analyzed common SNPs, common CNVs and rare CNVs and identified SNP alleles at three new loci associated with disease risk.

Capping the 5′ end of eukaryotic mRNAs with a 7-methylguanosine moiety enables efficient splicing, nuclear export and translation of mRNAs, and also limits their degradation by cellular exonucleases. Here, Canard and colleagues describe how viruses synthesize their own mRNA cap structures or steal them from host mRNAs, allowing efficient synthesis of viral proteins and avoidance of host innate immune responses.