SummaryBordetella pertussis establishes infection by attaching to epithelial cells of the respiratory tract. One of its adhesins is filamentous haemagglutinin (FHA), a 500-Å -long secreted protein that is rich in b-structure and contains two regions, R1 and R2, of tandem 19-residue repeats. Two models have been proposed in which the central shaft is (i) a hairpin made up of a pairing of two long antiparallel b-sheets; or (ii) a b-helix in which the polypeptide chain is coiled to form three long parallel b-sheets. We have analysed a truncated variant of FHA by electron microscopy (negative staining, shadowing and scanning transmission electron microscopy of unstained specimens): these observations support the latter model. Further support comes from detailed sequence analysis and molecular modelling studies. We applied a profile search method to the sequences adjacent to and between R1 and R2 and found additional 'covert' copies of the same motifs that may be recognized in overt form in the R1 and R2 sequence repeats. Their total number is sufficient to support the tenet of the b-helix model that the shaft domain -a 350 Å rod -should consist of a continuous run of these motifs, apart from loop inserts. The N-terminus, which does not contain such repeats, was found to be weakly homologous to cyclodextrin transferase, a protein of known immunoglobulin-like structure. Drawing on crystal structures of known b-helical proteins, we developed structural models of the coil motifs putatively formed by the R1 and R2 repeats. Finally, we applied the same profile search method to the sequence database and found several other proteins -all large secreted proteins of bacterial provenance -that have similar repeats and probably also similar structures.
<div class="section abstract"><div class="htmlview paragraph">The automotive acoustics arena is rich with application opportunities for carbon neutral or climate positive parts. The design of potential “green” NVH solutions however cannot compromise the intended acoustical performance of the vehicles. This paper investigates the acoustical needs of OEM vehicles with an emphasis to apply green solutions. The acoustic solutions proposal in this paper compares and contrasts barrier densities, sealing characteristics between traditional and carbon neutral acoustical barriers. It also compares important material properties. Furthermore, these comparisons demonstrate that vehicular acoustic performance need not be compromised as the industry moves towards more climate friendly initiatives. Lastly, the paper identifies an ideal application for planet friendly, carbon neutral NVH solutions. This is accomplished by using acoustical barrier applications that are production ready and commercially available today. None of these carbon neutral NVH solutions alter the anticipated acoustical performance of the target vehicle in a negative manner.</div></div>
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