Large protein complexes assemble spontaneously, yet their subunits do not prematurely form unwanted aggregates. This paradox is epitomized in the bacterial flagellar motor, a sophisticated rotary motor and sensory switch consisting of hundreds of subunits. Here we demonstrate that Escherichia coli FliG, one of the earliest-assembling flagellar motor proteins, forms ordered ring structures via domain-swap polymerization, which in other proteins has been associated with uncontrolled and deleterious protein aggregation. Solution structural data, in combination with in vivo biochemical cross-linking experiments and evolutionary covariance analysis, revealed that FliG exists predominantly as a monomer in solution but only as domain-swapped polymers in assembled flagellar motors. We propose a general structural and thermodynamic model for self-assembly, in which a structural template controls assembly and shapes polymer formation into rings.

Use of biofilm dispersing NO-donor compounds in combination with antibiotics has emerged as a promising new strategy for treating drug-resistant bacterial biofilm infections. This paper details the synthesis and preliminary evaluation of six cephalosporin-3'-diazeniumdiolates as biofilm-targeted NO-donor prodrugs. Each of the compounds is shown to selectively release NO following reaction with the bacteria-specific enzyme β-lactamase and to trigger dispersion of Pseudomonas aeruginosa biofilms in vitro.

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Copper (Cu) in an essential trace metal but it can also contaminate coastal waters at high 23 concentrations mainly from agricultural run-off and mining activities which are detrimental 24 to marine organisms including seagrasses. The molecular mechanisms driving Cu toxicity in 25 *Manuscript (clean -no tracked changes) Click here to view linked References seagrasses are not clearly understood yet. Here, we investigate the molecular responses of the 26 Australian seagrass, Z. muelleri at the whole transcriptomic level after 7 days of exposure to 27 250 μg Cu L -1 and 500 μg Cu L -1 . The leaf-specific whole transcriptome results showed a 28 concentration-dependent disturbance in chloroplast function, regulatory stress responses and 29 defence mechanisms. 30 This study provided new insights into the responses of seagrasses to trace metal stress and 31 reports possible candidate genes which can be considered as biomarkers to improve 32 conservation and management of seagrass meadows. 33 34 1. Introduction 35 Globally, coastal habitats are increasingly affected by a wide range of anthropogenic 36 discharges which often contain high levels of trace metals (Cambridge & McComb 1984; 37 Waycott et al. 2009; Leng et al. 2015). Once introduced to the marine environment, they are 38 taken up by seagrasses via roots and shoots (Howley et al. 2006). Consequently, as a food 39 source for many marine organisms, seagrasses represent a trophic pathway for the 40 distribution of trace metals into the marine food chain (