The distribution of ND genes in yeast mitochondrial genomes and the mitochondrial DNA structure of Pichia membranaefacens.

For long time, it has been believed that the yeast mitochondrial (mt) genome lacks NADH dehydrogenase subunit genes which are designated ND genes. However, our complete mtDNA sequencing of yeast Hansenula wingei led us to the first finding of seven mitochondrial ND genes. We investigated the distribution of ND genes in mtDNAs of other yeasts including Pichia membranaefaciens, Yarrowia lypolitica, Candida maltosa, Saccharomyces kluyveri and Saccharomyces exiguus. By Southern hybridization with probes of H. wingei's ND1, 2 and 5 genes, we detected positive signals on mtDNAs in P. membranaefaciens, Y. lypolitica, and C. maltosa. To confirm this, we cloned and sequenced DNA fragment of ND5 gene in P. membranaefaciens. We have discussed the sequence homology and genome structure.