Kluyveromyces marxianus small DNA fragments contain both autonomous replicative and centromeric elements that also function in Kluyveromyces lactis

Two fragments containing both an autonomous replicating sequence (ARS) and a centromere have been isolated and sequenced from the yeast Kluyveromyces marxianus. The ARS and centromeric core sequences are only 500 bp apart, but ARS activity could be separated from the centromeric sequences. Centromeric sequences are organized in a similar way to those of budding yeasts: two well-conserved elements: CDEI (5' TCACGTG 3') and CDEIII (5' TNTTCCGAAAGTWAAA 3'), are separated by a 165 bp AT-rich (+/- 90%) CDEII element whose length is twice that of Saccharomyces cerevisiae CDEII but almost identical to that of K. lactis. The ARS-core consensus sequence (5' TTTATTGTT 3') is also similar to that of K. lactis. Both ARS and centromeric elements function in this strain, albeit inefficiently, but not in S. cerevisiae. A third ARS-containing fragment with a different organization has been isolated and sequenced.