FlgN Is Required for Flagellum-Based Motility by Bacillus subtilis

The assembly of the bacterial flagellum is exquisitely controlled. Flagellar biosynthesis is underpinned by a specialized type III secretion system that allows export of proteins from the cytoplasm to the nascent structure. Bacillus subtilis regulates flagellar assembly using both conserved and species-specific mechanisms. Here, we show that YvyG is essential for flagellar filament assembly. We define YvyG as an orthologue of the Salmonella enterica serovar Typhimurium type III secretion system chaperone, FlgN, which is required for the export of the hook-filament junction proteins, FlgK and FlgL. Deletion of flgN (yvyG) results in a nonmotile phenotype that is attributable to a decrease in hag translation and a complete lack of filament polymerization. Analyses indicate that a flgK-flgL double mutant strain phenocopies deletion of flgN and that overexpression of flgK-flgL cannot complement the motility defect of a ΔflgN strain. Furthermore, in contrast to previous work suggesting that phosphorylation of FlgN alters its subcellular localization, we show that mutation of the identified tyrosine and arginine FlgN phosphorylation sites has no effect on motility. These data emphasize that flagellar biosynthesis is differentially regulated in B. subtilis from classically studied Gram-negative flagellar systems and questions the biological relevance of some posttranslational modifications identified by global proteomic approaches.     

A β‐amino acid modified heptapeptide containing a designed recognition element disrupts fibrillization of the amyloid β‐peptide

We study the complex formation of a peptide βAβAKLVFF, previously developed by our group, with Aβ(1–42) in aqueous solution. Circular dichroism spectroscopy is used to probe the interactions between βAβAKLVFF and Aβ(1–42), and to study the secondary structure of the species in solution. Thioflavin T fluorescence spectroscopy shows that the population of fibers is higher in βAβAKLVFF/Aβ(1–42) mixtures compared to pure Aβ(1–42) solutions. TEM and cryo‐TEM demonstrate that co‐incubation of βAβAKLVFF with Aβ(1–42) causes the formation of extended dense networks of branched fibrils, very different from the straight fibrils observed for Aβ(1–42) alone. Neurotoxicity assays show that although βAβAKLVFF alters the fibrillization of Aβ(1–42), it does not decrease the neurotoxicity, which suggests that toxic oligomeric Aβ(1–42) species are still present in the βAβAKLVFF/Aβ(1–42) mixtures. Our results show that our designed peptide binds to Aβ(1–42) and changes the amyloid fibril morphology. This is shown to not necessarily translate into reduced toxicity. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

SRAP Technique Efficiently Generates Polymorphisms in Puccinia striiformis Isolates

Wheat stripe rust, caused by the fungal pathogen Puccinia striiformis f.sp. tritici (PST), is a major disease of wheat in temperate‐cold climates. The identification of new markers would ease the procedure for evaluating the ongoing pathogen evolution. Twelve single pustule isolates were generated from samples of PST obtained in UK during 1987–2001. They were evaluated for their pathogenic behaviour on a set of differential cultivars and were analysed by sequence‐related amplified polymorphisms (SRAP) technique, to identify polymorphisms useful to evaluate variability among isolates. This is the first report of the application of SRAP technique to Uredinales order.     

The diet of Atlantic Yellow-legged Gulls (<Emphasis Type="Italic">Larus michahellis atlantis</Emphasis>) at an oceanic seabird colony: estimating predatory impact upon breeding petrels

The diet and breeding ecology of Yellow-legged Gulls (Larus michahellis atlantis) were studied on Selvagem Grande, North Atlantic in the nesting season of 2007. We collected and analyzed 715 pellets from adults. The most frequent prey were White-faced Storm-petrels (Pelagodroma marina; present on 40.8% of all pellets) and the endemic land snails (Theba macandrewiana; present on 36.5% of all pellets). Other birds, namely Cory’s Shearwaters (Calonectris diomedea), Macaronesian Shearwaters (Puffinus assimilis), Bulwer’s Petrels (Bulweria bulwerii), and Band-rumped Storm-petrels (Oceanodroma castro) were relatively less frequent, but overall, seabirds were present in ca. 50% of all pellets, representing an estimated 60.4% of all mass consumed by gulls. We estimate that the contribution of seabirds to the overall caloric balance accounted for 82.5% of all energy consumed. The number of gull pairs breeding on Selvagem Grande was 12 on 2005 and 2007. Breeding success was low (0.92 and 0.25 juveniles per breeding pair, respectively). Using a simple bioenergetics model, we estimate the breeding gull population to have the potential to consume approximately 4,847 adult/sub-adult seabirds in 3.5 months in order to meet its energetic requirements. The importance of the estimated predation levels is discussed and some management actions are suggested.     

Taura syndrome virus in specific pathogen-free Penaeus vannamei originating from Hawaii and in P. vannamei stocks farmed in France?

It is the opinion of the authors of the Comment on Do et al. (2006), that those authors incorrectly interpreted their test results, which are more likely the result of mislabeling of samples or within-laboratory contamination, and that the TSV isolates found in Penaeus vannamei in Korea in 2004 and 2005 did not originate from Hawaii as claimed by the authors, but from a country (or countries) in southeast Asia. Finally, we believe that the authors did not follow proper international guidelines, extend a professional courtesy to the supplier of the disputed shrimp sample, nor take a critical approach in interpreting their own data. It is unfortunate that the authors did not follow through with additional testing, or seek a second opinion from an independent laboratory, before implicating shrimp imported from Hawaii as the source of TSV in Korea.     

Structural analysis of Canavalia maritima and Canavalia gladiata lectins complexed with different dimannosides: new insights into the understanding of the structure-biological activity relationship in legume lectins

Plant lectins, especially those purified from species of the Leguminosae family, represent the best studied group of carbohydrate-binding proteins. The legume lectins from Diocleinae subtribe are highly similar proteins that present significant differences in the potency/efficacy of their biological activities. The structural studies of the interactions between lectins and sugars may clarify the origin of the distinct biological activities observed in this high similar class of proteins. In this way, this work presents a crystallographic study of the ConM and CGL (agglutinins from Canavalia maritima and Canavalia gladiata, respectively) in the following complexes: ConM/CGL:Man(alpha1-2)Man(alpha1-O)Me, ConM/CGL:Man(alpha1-3)Man(alpha1-O)Me and ConM/CGL:Man(alpha1-4)Man(alpha1-O)Me, which crystallized in different conditions and space group from the native proteins. The structures were solved by molecular replacement, presenting satisfactory values for R(factor) and R(free). Comparisons between ConM, CGL and ConA (Canavalia ensiformis lectin) binding mode with the dimannosides in subject, presented different interactions patterns, which may account for a structural explanation of the distincts biological properties observed in the lectins of Diocleinae subtribe.     

Crystallographic evidence for dioxygen interactions with iron proteins

The interaction of dioxygen with iron plays a key role in many important biological processes, such as dioxygen transport in the bloodstream and the reduction of dioxygen by iron in respiration. However, the catalytic mechanisms employed, for example in ligand oxidation, are not fully understood at the current time despite intensive biochemical, spectroscopic and structural studies. This review outlines the structural evidence obtained by X-ray crystallographic methods for the nature of the interactions between dioxygen and the metal in iron-containing proteins. Proteins involved in iron transport or electron transfer are not included.