Current Genetics

, Volume 34, Issue 1, pp 60–66 | Cite as

Construction of stable episomes in Cryptococcus neoformans

  • Ashok Varma
  • K. J. Kwon-Chung
ORIGINAL PAPER

Abstract

We report the generation of stable plasmids constructed by inserting specific DNA sequences into previously known unstable vectors. These sequences were obtained from a DNA library recovered from a previously reported stable minichromosome created by electroporative transformation in Cryptococcus neoformans (Varma and Kwon-Chung 1994). A 6-kb insert from this minichromosome significantly enhanced both the frequencies at which URA5 transformants were obtained as well as the stability of their uracil prototrophy on non-selective media. A 1.5-kb sequence of this insert contained telomeric sequence repeats which when introduced into plasmids resulted in significant increases in transformation frequency. A 1081-bp sequence (STAB), present in the remainder of the insert, had an ARS-like function enhancing the episomal maintenance of plasmids in the transformants regardless of the gene (ADE2/URA5) used as a selection marker.

Key words Transformation Yeast Plasmids Cryptococcus neoformans 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Ashok Varma
    • 1
  • K. J. Kwon-Chung
    • 1
  1. 1.Molecular Microbiology Section, Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, Building 10, Room 11C304, National Institutes of Health, Bethesda, MD 20892, USA Tel.: +1-301-496 1602 Fax: +1-301-402 1003 e-mail: June_Kwon-Chung@nih.govUS

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