Complete DNA sequence of yeast chromosome XI

The complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome XI has been determined. In addition to a compact arrangement of potential protein coding sequences, the 666,448-base-pair sequence has revealed general chromosome patterns; in particular, alternating regional variations in average base composition correlate with variations in local gene density along the chromosome. Significant discrepancies with the previously published genetic map demonstrate the need for using independent physical mapping criteria.

The RHO4a and NUD1 genes on Saccharomyces cerevisiae chromosome XI

Sequence analysis of a 4 kb fragment from the right arm of Saccharomyces cerevisiae chromosome XI, in combination with Northern hybridization experiments revealed the presence of two genes, designated RHO4a and NUD1. The first gene encodes a 32 kDa protein showing significant sequence similarity with members of the ras family. Its 3'-terminal sequence is virtually identical to a sequence published previously as the RHO4 gene [Matsui and Toh-e, Gene 114 (1992), 43-49], which, however, appears to start at an internal ATG codon. The RHO4a sequence also overlaps the 5'-terminal sequence of the RNC1 gene [Chow et al., Nucl. Acids Res. 20 (1992), 5215-5221] proposed to encode the yeast yNucR endo/exonuclease. The remainder of this RNC1 gene overlaps with the 5'-end of the NUD1 gene. However, the RNC1 sequence lacks a portion of 276 bp that in our fragment is part of the intergenic region separating RHO4a and NUD1. From these results we conclude that the proposed RNC1 gene is the result of a cloning artefact and that the yNucR protein is instead encoded by the NUD1 gene.