Review Articles

Type III secretion systems (T3SSs) are protein transport nanomachines that resemble molecular syringes and are found in numerous Gram-negative bacterial species. This Review summarizes our current understanding of the structure and function of these important protein secretion systems, incorporating new advances from cryo-electron microscopy and integrative imaging studies.

Antibiotic resistance is a global problem that threatens individual and societal well-being. In this Review, Crofts, Gasparrini and Dantas summarize how research has changed from the discovery of resistant bacteria to community-level resistome studies, and they propose future therapeutic and surveillance approaches.

Coral reefs are complex ecosystems that are populated by diverse microorganisms. In this Review, Vega Thurberet al. summarize the diversity of reef viruses that infect corals and their associated microbiota, and highlight their roles in coral disease and reef decline.

Circadian rhythms enable cells to anticipate cyclic changes in their environment. In this Review, Johnsonet al. explore timekeeping systems that range from prototypical circadian clocks to hourglass timers and their role in different bacteria, including cyanobacteria and members of the microbiota.

Trypanosomatid parasites can cause life-threatening diseases, such as human African trypanosomiasis, leishmaniasis and Chagas disease. In this Review, Gilbert and colleagues discuss the drug discovery landscape and describe some of the challenges that are involved in the development of new drugs to treat these diseases.

The discovery of the giant amoebal virus mimivirus, in 2003, opened up a new area of virology. Extended studies, including those of mimiviruses, have since revealed that these viruses have genetic, proteomic and structural features that are more complex than those of conventional viruses.

In this Review, Chandrangsuet al. discuss recent insights into metalloregulatory systems that are used by bacteria and how they respond to metal limitation and intoxication, as well as how these systems influence host–pathogen interactions.

The respiratory tract spans from the nostrils to the lung alveoli and these distinct niches host a diverse microbiota. In this Review, Man, de Steenhuijsen Piters and Bogaert discuss the role of the respiratory microbiota in the maintenance of human health.

Understanding the ecology and function of dry-adapted communities is important for understanding and preventing desertification. In this Review, Lebre, De Maayer and Cowan discuss the adaptations that enable xerotolerant bacteria to survive extreme dry conditions and highlight insights from recent metagenomic and transcriptomic studies.

Pathogenic leptospires are the bacterial agents of leptospirosis, which is an emerging zoonotic disease that affects both animals and humans worldwide. In this Review, the recent advances in our understanding of the epidemiology, taxonomy, genomics and the molecular basis of virulence in leptospires, and of how these properties contribute to the pathogenesis of leptospirosis, are discussed.

Cyclic dinucleotides are highly versatile signalling molecules that control important biological processes in bacteria, including motility, virulence, biofilm formation and cell cycle progression. In this Review, Jenal and colleagues discuss the molecular principles of cyclic di-GMP (c-di-GMP) synthesis and degradation, and the cellular functions that are exerted by c-di-GMP-binding effectors and their diverse targets.

Recent studies have provided insights into the antagonistic roles of cyclic-di-GMP (c-di-GMP) and the alarmones guanosine tetraphosphate and guanosine pentaphosphate (collectively referred to as (p)ppGpp) in the regulation of the cell cycle in Alphaproteobacteria. In this Review, Viollier and colleagues discuss how those second messengers control the initiation of DNA replication and cytokinesis by modulating the synthesis and proteolysis of key regulators of the cell cycle.

Bacteria have to overcome many obstacles to invade the meninges from the bloodstream. This Review considers how extracellular pathogens such asNeisseria meningitides and Streptococcus pneumoniaebypass the blood–brain barriers, the understanding of which may lead to improved methods for delivering drugs into the brain.

In addition to viruses, bacteria such asHelicobacter pylori and Salmonella enterica subsp. entericaserovar Typhi have been linked to cancer development. Progress has been made in our understanding of how bacterial effectors contribute to cancer directly by influencing host cell signalling pathways and indirectly by causing tissue damage and inflammatory responses.

Entry into the nucleus and integration into the host cell are key steps during HIV-1 infection. In this Review, Lusic and Siliciano discuss viral and host factors that influence HIV-1 integration and how it can be targeted therapeutically.

Cellulosomes are sophisticated multicomponent complexes that are used by bacteria to degrade cellulose from plant cell walls. In this review, Artzi, Bayer and Moraïs explore the structural and functional diversity of cellulosomes and their applications; for example, in microbial biofuel production.

In this Review, Tsirigotakiet al. discuss recent biochemical, structural and mechanistic insights that have been gained into the consecutive steps of the general secretory (Sec) pathway. They focus on the architecture and dynamics of SecYEG and its regulation by ribosomes and SecA, and present current models of the mechanisms and energetics of the Sec-pathway-dependent secretion process in bacteria.

In this Review, De Nizet al. discuss the contribution of key imaging tools to advances in our understanding of Plasmodiumspp. biology and host–pathogen interactions over the past decade. These advances, pertaining to parasite structure and motility, as well as the liver and blood stages, have led to paradigm shifts in our knowledge of malaria.

In this Review, Noble and colleagues discuss the characteristics of the classic cell types ofCandida albicans— yeast, hyphae, pseudohyphae and chlamydospores — as well as newly identified yeast-like morphotypes, including grey and gastrointestinally induced transition (GUT) cell types, and highlight emerging knowledge about their associations with different host niches and propensities towards virulence versus commensalism.

Protists are an important part of the marine food web. In this Review, Caronet al. summarize recent insights from transcriptomic studies of cultured and free-living protists and discuss how these findings highlight the functions and interactions of these single-celled eukaryotes in the global oceans.