rptA, a novel gene from Ensifer (Sinorhizobium) meliloti involved in conjugal transfer

Authors

  • Mariano Pistorio,

    Corresponding author
    • IBBM – Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata – Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
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  • Gonzalo A. Torres Tejerizo,

    1. IBBM – Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata – Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
    Current affiliation:
    1. Programa de Ingeniería Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México. Av. Universidad 1001, Cuernavaca, Morelos, Mexico
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  • María Florencia Del Papa,

    1. IBBM – Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata – Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
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  • María de los Angeles Giusti,

    1. IBBM – Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata – Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
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  • Mauricio Lozano,

    1. IBBM – Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata – Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
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  • Antonio Lagares

    1. IBBM – Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata – Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
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Correspondence: Mariano Pistorio, IBBM – Instituto de Biotecnología y Biología Molecular, CCT-CONICET-La Plata – Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900) La Plata, Argentina. Tel./fax: +54 221 4229777; e-mail: pistorio@biol.unlp.edu.ar

Abstract

We approached the identification of Ensifer (Sinorhizobium) meliloti conjugal functions by random Tn5-B13 mutagenesis of the pSmeLPU88a plasmid of E. meliloti strain LPU88 and the subsequent selection of those mutants that had lost the ability to mobilize the small plasmid pSmeLPU88b. The Tn5-B13-insertion site of one of the mutants was cloned as an EcoRI-restricted DNA fragment that after subsequent isolation and sequencing demonstrated that a small open reading frame of 522 bp (designated rptA, for rhizobium plasmid transfer A) had been disrupted. The predicted gene product encoded by the rptA sequence shows a significant similarity to two hypothetical proteins of the plasmid pSmed03 of Ensifer medicae WSM419 and other rhizobia plasmids. No significant similarity was found to any protein sequence of known function registered in the databases. Although the rptA gene was required for pSmeLPU88b-plasmid mobilization in the strain 2011 background, it was not required in the original strain LPU88 background.

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