The mitochondrial genome of yeast Hansenula wingei encodes NADH dehydrogenase subunit genes ND4L and ND5

Genes homologous to those encoding mitochondrial NADH dehydrogenase subunits ND4L and ND5 in filamentous fungi were identified in the mitochondrial genome of a budding yeast, Hansenula wingei. The structure and expression of these genes were investigated. The H. wingei ND4L gene is 282 by long, and potentially codes for a polypeptide of 94 amino acids. The putative ND4L protein sequence shares about 46% homology with the analogous mitochondrial proteins of filamentous fungi. The H. wingei ND5 gene is 1935 by long, and encodes a 645-residue polypeptide. The derived ND5 protein shares about 38% sequence homology with the analogue in filamentous fungi. The ND4L and ND5 genes have no intervening sequence, and form a gene cluster in the order of 5′-ND4L-ND5-3′. A presumptive mature dicistronic or polycistronic transcript of these genes was detected by Northern blot hybridization. These results strongly indicate that these ND4L and ND5 genes are active. As far as we are aware, this is the first report on the identification of mitochondrially encoded ND genes in yeast.