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      The Kiwifruit Emerging Pathogen Pseudomonas syringae pv. actinidiae Does Not Produce AHLs but Possesses Three LuxR Solos

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          Pseudomonas syringae pv. actinidiae ( Psa) is an emerging phytopathogen causing bacterial canker disease in kiwifruit plants worldwide. Quorum sensing (QS) gene regulation plays important roles in many different bacterial plant pathogens. In this study we analyzed the presence and possible role of N-acyl homoserine lactone (AHL) quorum sensing in Psa. It was established that Psa does not produce AHLs and that a typical complete LuxI/R QS system is absent in Psa strains. Psa however possesses three putative luxR solos designated here as PsaR1, PsaR2 and PsaR3. PsaR2 belongs to the sub-family of LuxR solos present in many plant associated bacteria (PAB) that binds and responds to yet unknown plant signal molecules. PsaR1 and PsaR3 are highly similar to LuxRs which bind AHLs and are part of the canonical LuxI/R AHL QS systems. Mutation in all the three luxR solos of Psa showed reduction of in planta survival and also showed additive effect if more than one solo was inactivated in double mutants. Gene promoter analysis revealed that the three solos are not auto-regulated and investigated their possible role in several bacterial phenotypes.

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          Most cited references 75

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          I-TASSER server for protein 3D structure prediction

           Yang Zhang (2008)
          Background Prediction of 3-dimensional protein structures from amino acid sequences represents one of the most important problems in computational structural biology. The community-wide Critical Assessment of Structure Prediction (CASP) experiments have been designed to obtain an objective assessment of the state-of-the-art of the field, where I-TASSER was ranked as the best method in the server section of the recent 7th CASP experiment. Our laboratory has since then received numerous requests about the public availability of the I-TASSER algorithm and the usage of the I-TASSER predictions. Results An on-line version of I-TASSER is developed at the KU Center for Bioinformatics which has generated protein structure predictions for thousands of modeling requests from more than 35 countries. A scoring function (C-score) based on the relative clustering structural density and the consensus significance score of multiple threading templates is introduced to estimate the accuracy of the I-TASSER predictions. A large-scale benchmark test demonstrates a strong correlation between the C-score and the TM-score (a structural similarity measurement with values in [0, 1]) of the first models with a correlation coefficient of 0.91. Using a C-score cutoff > -1.5 for the models of correct topology, both false positive and false negative rates are below 0.1. Combining C-score and protein length, the accuracy of the I-TASSER models can be predicted with an average error of 0.08 for TM-score and 2 Å for RMSD. Conclusion The I-TASSER server has been developed to generate automated full-length 3D protein structural predictions where the benchmarked scoring system helps users to obtain quantitative assessments of the I-TASSER models. The output of the I-TASSER server for each query includes up to five full-length models, the confidence score, the estimated TM-score and RMSD, and the standard deviation of the estimations. The I-TASSER server is freely available to the academic community at .
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            TM-align: a protein structure alignment algorithm based on the TM-score

            We have developed TM-align, a new algorithm to identify the best structural alignment between protein pairs that combines the TM-score rotation matrix and Dynamic Programming (DP). The algorithm is ∼4 times faster than CE and 20 times faster than DALI and SAL. On average, the resulting structure alignments have higher accuracy and coverage than those provided by these most often-used methods. TM-align is applied to an all-against-all structure comparison of 10 515 representative protein chains from the Protein Data Bank (PDB) with a sequence identity cutoff <95%: 1996 distinct folds are found when a TM-score threshold of 0.5 is used. We also use TM-align to match the models predicted by TASSER for solved non-homologous proteins in PDB. For both folded and misfolded models, TM-align can almost always find close structural analogs, with an average root mean square deviation, RMSD, of 3 Å and 87% alignment coverage. Nevertheless, there exists a significant correlation between the correctness of the predicted structure and the structural similarity of the model to the other proteins in the PDB. This correlation could be used to assist in model selection in blind protein structure predictions. The TM-align program is freely downloadable at .
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              Four new derivatives of the broad-host-range cloning vector pBBR1MCS, carrying different antibiotic-resistance cassettes.

              Four new antibiotic-resistant derivatives of the broad-host-range (bhr) cloning vector pBBR1MCS have been constructed. These new plasmids have several advantages over many of the currently available bhr vectors in that: (i) they are relatively small (< 5.3 kb), (ii) they possess an extended multiple cloning site (MCS), (iii) they allow direct selection of recombinant plasmid molecules in Escherichia coli via disruption of the LacZ alpha peptide, (iv) they are mobilizable when the RK2 transfer functions are provided in trans and (v) they are compatible with IncP, IncQ and IncW group plasmids, as well as with ColE1- and P15a-based replicons.

                Author and article information

                Role: Editor
                PLoS One
                PLoS ONE
                PLoS ONE
                Public Library of Science (San Francisco, USA )
                31 January 2014
                : 9
                : 1
                [1 ]International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
                [2 ]Research Centre for Fruit Crops, Agricultural Research Council, Roma, Italy
                [3 ]Research Unit for Fruit Trees, Agricultural Research Council, Caserta, Italy
                [4 ]Istituto di Cristallografia, Consiglio Nazionale delle Ricerche, U.O.S di Trieste, Trieste, Italy
                The Scripps Research Institute and Sorrento Therapeutics, Inc., United States of America
                Author notes

                Competing Interests: The authors have declared that no competing interests exist.

                Conceived and designed the experiments: HKP VV. Performed the experiments: HKP PF SC. Analyzed the data: HKP PF VV SC MS DL. Contributed reagents/materials/analysis tools: HKP PF VV MS DL. Wrote the paper: HKP DL SC VV.


                This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

                Page count
                Pages: 14
                HKP was funded by an ICGEB Pre-doctoral fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
                Research Article
                Bacterial Pathogens
                Gram Negative
                Host-Pathogen Interaction
                Microbial Growth and Development
                Plant Microbiology
                Molecular Cell Biology
                Signal Transduction
                Mechanisms of Signal Transduction
                Plant Science
                Plant Pathology
                Plant Pathogens
                Plant Microbiology
                Infectious Diseases
                Bacterial Diseases
                Pseudomonas Infections



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