The crystal structure of the motor domain of Dictyostelium discoideum myosin‐IE, a monomeric unconventional myosin, was determined. The crystallographic asymmetric unit contains four independently ...resolved molecules, highlighting regions that undergo large conformational changes. Differences are particularly pronounced in the actin binding region and the converter domain. The changes in position of the converter domain reflect movements both parallel to and perpendicular to the actin axis. The orientation of the converter domain is ∼30° further up than in other myosin structures, indicating that MyoE can produce a larger power stroke by rotating its lever arm through a larger angle. The role of extended loops near the actin‐binding site is discussed in the context of cellular localization. The core regions of the motor domain are similar, and the structure reveals how that core is stabilized in the absence of an N‐terminal SH3‐like domain.
Helicoverpa armigera and Helicoverpa zea are major caterpillar pests of Old and New World agriculture, respectively. Both, particularly H. armigera, are extremely polyphagous, and H. armigera has ...developed resistance to many insecticides. Here we use comparative genomics, transcriptomics and resequencing to elucidate the genetic basis for their properties as pests.
We find that, prior to their divergence about 1.5 Mya, the H. armigera/H. zea lineage had accumulated up to more than 100 more members of specific detoxification and digestion gene families and more than 100 extra gustatory receptor genes, compared to other lepidopterans with narrower host ranges. The two genomes remain very similar in gene content and order, but H. armigera is more polymorphic overall, and H. zea has lost several detoxification genes, as well as about 50 gustatory receptor genes. It also lacks certain genes and alleles conferring insecticide resistance found in H. armigera. Non-synonymous sites in the expanded gene families above are rapidly diverging, both between paralogues and between orthologues in the two species. Whole genome transcriptomic analyses of H. armigera larvae show widely divergent responses to different host plants, including responses among many of the duplicated detoxification and digestion genes.
The extreme polyphagy of the two heliothines is associated with extensive amplification and neofunctionalisation of genes involved in host finding and use, coupled with versatile transcriptional responses on different hosts. H. armigera's invasion of the Americas in recent years means that hybridisation could generate populations that are both locally adapted and insecticide resistant.
Molecular motors move unidirectionally along polymer tracks, producing movement and force in an ATP‐dependent fashion. They achieve this by amplifying small conformational changes in the ...nucleotide‐binding region into force‐generating movements of larger protein domains. We present the 2.8 Å resolution crystal structure of an artificial actin‐based motor. By combining the catalytic domain of myosin II with a 130 Å conformational amplifier consisting of repeats 1 and 2 of α‐actinin, we demonstrate that it is possible to genetically engineer single‐polypeptide molecular motors with precisely defined lever arm lengths and specific motile properties. Furthermore, our structure shows the consequences of mutating a conserved salt bridge in the nucleotide‐binding region. Disruption of this salt bridge, which is known to severely inhibit ATP hydrolysis activity, appears to interfere with formation of myosin's catalytically active ’closed' conformation. Finally, we describe the structure of α‐actinin repeats 1 and 2 as being composed of two rigid, triple‐helical bundles linked by an uninterrupted α‐helix. This fold is very similar to the previously described structures of α‐actinin repeats 2 and 3, and α‐spectrin repeats 16 and 17.
A series of systematically varied (η3‐1,3‐dialkylallyl)palladium complexes of (4S)‐2‐(2‐diphenylphosphanyl)phenyl‐4,5‐dihydrooxazole (PHOX) ligands were characterized by X‐ray crystal structure ...analysis and NMR spectroscopy. Complexes with identical substituents in the 1,3‐positions of the allyl group can form eight stereoisomers. In solution four to six isomers were observed and their conformations assigned with the aid of NOE experiments. The dynamic behavior of the complexes was analyzed. In addition, quantum‐chemical calculations (restricted Hartree–Fock (HF), density functional theory (DFT)) were carried out and gave satisfactory agreement with experimental findings.
Eight possible stereoisomers (four exo and four endo) exist for (η3‐allyl)palladium complexes with (4S)‐2‐(2‐diphenylphosphanyl)phenyl‐4,5‐dihydrooxazole ligands (see scheme). By means of multinuclear 2D NMR spectroscopy, the populations of the various isomers and the dynamic behavior of the complexes in solution, both relevant to the outcome of asymmetric allylic substitutions, were determined for a series of R and R′. In addition, quantum‐chemical calculations reproduced these data sufficiently well to allow new chiral ligands for these reactions to be assessed theoretically.
Summary Background The ideal closure technique of the pancreas after distal pancreatectomy is unknown. We postulated that standardised closure with a stapler device would prevent pancreatic fistula ...more effectively than would a hand-sewn closure of the remnant. Methods This multicentre, randomised, controlled, parallel group-sequential superiority trial was done in 21 European hospitals. Patients with diseases of the pancreatic body and tail undergoing distal pancreatectomy were eligible and were randomly assigned by central randomisation before operation to either stapler or hand-sewn closure of the pancreatic remnant. Surgical performance was assessed with intraoperative photo documentation. The primary endpoint was the combination of pancreatic fistula and death until postoperative day 7. Patients and outcome assessors were masked to group assignment. Interim and final analysis were by intention to treat in all patients in whom a left resection was done. This trial is registered, ISRCTN18452029. Findings Between Nov 16, 2006, and July 3, 2009, 450 patients were randomly assigned to treatment groups (221 stapler; 229 hand-sewn closure), of whom 352 patients (177 stapler, 175 hand-sewn closure) were analysed. Pancreatic fistula rate or mortality did not differ between stapler (56 32% of 177) and hand-sewn closure (49 28% of 175; OR 0·84, 95% CI 0·53–1·33; p=0·56). One patient died within the first 7 days after surgery in the hand-sewn group; no deaths occurred in the stapler group. Serious adverse events did not differ between groups. Interpretation Stapler closure did not reduce the rate of pancreatic fistula compared with hand-sewn closure for distal pancreatectomy. New strategies, including innovative surgical techniques, need to be identified to reduce this adverse outcome. Funding German Federal Ministry of Education and Research.
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