Polydopamine (PDA) formed by the oxidation of dopamine is an important polymer, in particular, for coating various surfaces. It is composed of dihydroxyindole, indoledione, and dopamine units, which are assumed to be covalently linked. Although PDA has been applied in a manifold way, its structure is still under discussion. Similarities have been observed in melanins/eumelanins as naturally occurring, deeply colored polymer pigments derived from L-DOPA. Recently, an alternative structure was proposed for PDA wherein dihydroxyindoline, indolinedione, and eventually dopamine units are not covalently linked to each other but are held together by hydrogen bonding between oxygen atoms or π stacking. In this study, we show that this structural proposal is very unlikely to occur taking into account unambiguous results obtained by different analytical methods, among them (13)C CPPI MAS NMR (cross-polarization polarization-inversion magic angle spinning NMR), (1)H MAS NMR (magic angle spinning NMR), and ES-HRMS (electrospray ionization high-resolution mass spectrometry) for the first time in addition to XPS (X-ray photoelectron spectroscopy) and FTIR spectroscopy. The results give rise to a verified structural assignment of PDA wherein dihydroxyindole and indoledione units with different degrees of (un)saturation are covalently linked by C-C bonds between their benzene rings. Furthermore, proof of open-chain (dopamine) monomer units in PDA is provided. Advanced DFT calculations imply the arrangements of several PDA chains preferably by quinone-hydroquinone-type interactions in a parallel or antiparallel manner. From all of these results, a number of hypotheses published before could be experimentally supported or were found to be contradictory, thus leading to a better understanding of the PDA structure.

Adhesion-type G protein-coupled receptors (aGPCRs), a large molecule family with over 30 members in humans, operate in organ development, brain function and govern immunological responses. Correspondingly, this receptor family is linked to a multitude of diverse human diseases. aGPCRs have been suggested to possess mechanosensory properties, though their mechanism of action is fully unknown. Here we show that the Drosophila aGPCR Latrophilin/dCIRL acts in mechanosensory neurons by modulating ionotropic receptor currents, the initiating step of cellular mechanosensation. This process depends on the length of the extended ectodomain and the tethered agonist of the receptor, but not on its autoproteolysis, a characteristic biochemical feature of the aGPCR family. Intracellularly, dCIRL quenches cAMP levels upon mechanical activation thereby specifically increasing the mechanosensitivity of neurons. These results provide direct evidence that the aGPCR dCIRL acts as a molecular sensor and signal transducer that detects and converts mechanical stimuli into a metabotropic response.DOI: http://dx.doi.org/10.7554/eLife.28360.001

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CP81 is a virulent Campylobacter group III phage whose linear genome comprises 132,454 bp. At the nucleotide level, CP81 differs from other phages. However, a number of its structural and replication/recombination proteins revealed a relationship to the group II Campylobacter phages CP220/CPt10 and to T4-type phages. Unlike the T4-related phages, the CP81 genome does not contain conserved replication and virion modules. Instead, the respective genes are scattered throughout the phage genome. Moreover, most genes for metabolic enzymes of CP220/CPt10 are lacking in CP81. On the other hand, the CP81 genome contains nine similar genes for homing endonucleases which may be involved in the attrition of the conserved gene order for the virion core genes of T4-type phages. The phage apparently possesses an unusual modification of C or G bases. Efficient cleavage of its DNA was only achieved with restriction enzymes recognizing pure A/T sites. Uncommonly, phenol extraction leads to a significant loss of CP81 DNA from the aqueous layer, a property not yet described for other phages belonging to the T4 superfamily.Campylobacteriosis is a worldwide zoonosis. There are probably more than two million Campylobacter infections in humans annually in the United States. Also, in developing countries, infections with Campylobacter jejuni are very frequent in children, and symptomatic infections early in life are followed later by asymptomatic infections. The bacteria are common commensals of the gastrointestinal tract of various mammals and birds. Consumption of undercooked meats, especially poultry, has been associated with Campylobacter infections (44). The prevalence of Campylobacter-positive chicken is generally high, and transmission of Campylobacter from bird to bird occurs rapidly (25). Intervention strategies mainly focus on biosecurity measures (e.g., improvement of personal hygiene, avoiding of mixed farming, and control of rodents and insects) and postslaughter decontamination of poultry carcasses (19). Since these measures are expensive and not always efficient and since suitable vaccines are not available, bacteriophages have been proposed to reduce the Campylobacter counts on chicken. Indeed, phage administration in the laboratory reduced C. jejuni colonization of the broiler gut and the contamination on chicken skin by several orders of magnitude (3,6,16,20,29,50).Phages intended for therapeutic applications or for the control of pathogens in food production have to fulfill a number of requirements. First and foremost, phages have to be safe in order to avoid any undesired side effect. Therefore, a basic understanding of the biology and genetics of the phage to be used is mandatory. A minimal standard is the acquisition of the genome sequence of the phage to exclude undesired genes. Unfortunately, up to now, genome sequences of Campylobacter phages are scarce. Most Campylobacter phages have been investigated only with respect to their host ranges, morphology, and genome size (3,4,11,16,22,26,30). Almost all Campyloba...