Review Articles in 2011

The peptidoglycan sacculus maintains bacterial cell shape and provides mechanical strength to resist osmotic challenge. In this Review, Vollmer and colleagues describe recent insights into the mechanisms of peptidoglycan synthesis in Gram-negative bacteria and how this process is regulated by cytoskeletal and outer-membrane components.

The replication of positive-sense RNA ((+)RNA) viruses involves numerous interactions between the RNA and proteins of the virus and proteins, membranes and lipids of the host. Host factors are thus key determinants of viral pathology as well as viral evolution. In this Review, Nagy and Pogany outline our current understanding of the host factors that facilitate the replication of (+)RNA viruses.

Proteasomes exist in all domains of life and serve to degrade proteins. In eukaryotes, proteins are primarily targeted for proteasomal degradation through the addition of ubiquitin. Similarly, archaea and bacteria modify proteins with Pup and Samps, respectively, and this may also serve as a signal for proteasomal degradation.

Candida albicanscan grow as unicellular budding yeast cells and as filamentous hyphae. Mihai Netea and colleagues discuss the molecular mechanisms that drive this dimorphism, the changes that lead to differential interaction with the host, and the immunological mechanisms that discriminate between tissue colonization and invasion.

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.

Dispersal is an essential stage in the 'life cycle' of many bacterial biofilms and is carefully regulated. McDougaldet al. describe the factors that control this step, and place this process in an ecological context with a comparison to analogous eukaryotic life cycles.

The genomics era has provided the opportunity for detailed investigations into the effects of the gut microbiota on the host mucosa. Bron, van Baarlen and Kleerebezem describe the features of probiotic bacteria that affect the mucosal immune system, and discuss the effect of the molecular characteristics of the host's mucosa on the response to these bacteria.

The nucleotide cyclic AMP is used by many organisms as a second messenger in signal transduction pathways to sense environmental changes. In this Review, McDonough and Rodriguez discuss the many roles of cAMP in bacterial and eukaryotic pathogens, from the regulation of virulence to the manipulation of host defences.

When a bacterium transitions from a free-living to a symbiotic lifestyle, the pressure to maintain certain genes decreases and the lack of genetic exchange allows deleterious mutations to accumulate. Here, McCutcheon and Moran describe the extraordinarily small genomes of several recently characterized symbionts and discuss the processes that allowed these genomes to shrink.

In filamentous fungi, actin is organized in higher-order structures (patches, rings and cables) that generate forces or serve as tracks for the intracellular transport of vesicles and organelles. Here, Read and colleagues discuss the contribution that recent live-cell imaging and mutational studies have made to our understanding of these processes.

Cellular pathways can be controlled through proteolysis, which allows rapid responses to changes in the environment. However, proteolysis is irreversible, so it must be carefully regulated. Here, Ron and colleagues describe how proteolysis modifies cellular behaviour and the ways in which it is controlled.

Viruses rely on the translation machinery of the host cell to produce the proteins that are essential for their replication. Here, Walsh and Mohr discuss the diverse strategies by which viruses subvert the host protein synthesis machinery and regulate the translation of viral mRNAs.

The compatible solute dimethylsulphoniopropionate (DMSP) has important roles in the ecology and biogeochemistry of marine environments, as do some of its breakdown products. In this Review, Johnston and colleagues describe the recent advances in our understanding of the microorganisms, enzymes and genes involved in DMSP catabolism.

Non-transcriptional events can have a large effect on the dynamics of regulatory processes. Here, Ray, Tabor and Igoshin describe how post-transcriptional and post-translational events can affect the performance of regulatory processes in bacteria.

Many microorganisms produce secondary metabolites to protect their molecular constituents from the damaging effects of ultraviolet radiation. Here, Gao and Garcia-Pichel describe our current understanding of the best known examples of these microbial ultraviolet sunscreens, including their biosynthesis, regulation and potential applications.

Until recently, it was though that the microbial degradation of aromatic compounds was absolutely dependent on the use of molecular oxygen for ring cleavage. However, as described here by Fuchs and colleagues, microorganisms have other ways of breaking down these compounds when oxygen is scarce or absent.

Under normal conditions, the components of a toxin–antitoxin (TA) system form a stable complex, blocking toxin activity. However, when the cell is stressed, the antitoxin is degraded, freeing the toxin to cause damage. Here, Yamaguchi and Inouye describe the TA systems found inEscherichia coliand their role in regulating cell growth and death.

Trichodermaspp. are common filamentous fungi that interact with other fungi, animals and plants and are used for biological control of plant diseases. In this Review, Kubicek and colleagues highlight how saprotrophy and parasitism on other fungi may have driven the evolution of the interactions ofTrichodermaspp. with plants and animals.

Group AStreptococcuscan cause devastating infections with high mortality rates. Here, Walker and colleagues describe the bacterial virulence factors that allow this species to infect tissues and escape destruction in neutrophils, and discuss how genetic changes in a two-component regulatory system promote pathogenicity.

In response to certain environmental cues, the unicellular budding yeastCandida albicanscan also grow as either a pseudohyphal or a hyphal form. In this Review, Sudbery describes the signal transduction pathways and cellular mechanisms that drive polarized hyphal growth and the role of this growth in disease.