A gene (KlCCA1) encoding ATP(CTP):tRNA specific tRNA nucleotidyltransferase (EC 2.7.7.25) was isolated from Kluyveromyces lactis by complementation of the Saccharomyces cerevisiae cca1-1 mutation. Sequencing of a 2665 bp EcoRI-SpeI restriction fragment revealed an open reading frame potentially encoding a protein of 489 amino acids with 57% sequence similarity to its S. cerevisiae homologue. Southern hybridization revealed a single copy of KlCCA1 in the K. lactis genome. KlCCA1 was able to complement both the mitochondrial and cytosolic defects in the cca1-1 mutant, suggesting that, as in S. cerevisiae, the K. lactis gene encodes a sorting isozyme that is targeted to mitochondria and the nucleus and/or cytosol. An altered KlCCA1 gene encoding a tRNA nucleotidyltransferase that lacked its first 35 amino acids was able to complement the nuclear/cytosolic but not the mitochondrial defect in the S. cerevisiae cca1-1 mutant, suggesting that the 35 amino-terminal amino acids are necessary for targeting to mitochondria but are not required for enzyme activity. Our results suggest that the mechanisms for production and distribution of mitochondrial and nuclear/cytosolic tRNA nucleotidyltransferase in K. lactis differ from those seen in S. cerevisiae.

• PMID: 10870105
• DOI full text
• PubMed
• PubTator

Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Deng XY, Hanic-Joyce PJ, Joyce PB

Primary Lit For

Additional Lit For

Review For