Journal of Bacteriology, February 1999, p. 1005-1013, Vol. 181, No. 3
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Biotechnology Research Division,
Received 29 June 1998/Accepted 23 November 1998
A family of multiple autonomously replicating sequences (ARSs)
which are located at several chromosomal ends of Hansenula polymorpha DL-1 has been identified and characterized. Genomic Southern blotting with an ARS, HARS36, originating from the end of a
chromosome, as a probe showed several homologues in the genome of
H. polymorpha. Nucleotide sequences of the three fragments obtained by a selective cloning for chromosomal ends were nearly identical to that of HARS36. All three fragments harbored an ARS motif
and ended with 18 to 23 identical repetitions of 5'-GGGTGGCG-3' which resemble the telomeric repeat sequence in other eukaryotes. Transformation of H. polymorpha with nonlinearized plasmids
containing the newly obtained telomeric ARSs almost exclusively
resulted in the targeted integration of a single copy or multiple
tandem copies of the plasmid into the chromosomes. The sensitivity to exonuclease Bal31 digestion of the common DNA fragment
in all integrants confirmed the telomeric origin of HARS36 homologues, suggesting that several chromosomal ends, if not all of them, consisted
of the same ARS motif and highly conserved sequences observed in
HARS36. Even though the frequencies of targeted recombination were
varied among the ends of the chromosomes, the overall frequency was over 96%. The results suggested that the integration of the plasmids containing telemeric ARSs occurred largely through
homologous recombination at the telomeric repeats, which serve as
high-frequency recombination targets.
*
Corresponding author. Mailing address: Biotechnology
Research Division, Korea Research Institute of Bioscience and
Biotechnology, Yusong, P.O. Box 115, Taejon 305-600, Korea. Phone:
82-42-860-4005. Fax: 82-42-860-4592. E-mail:
rheesk{at}kribb4680.kribb.re.kr.
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