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A gene encoding the 16-kDa proteolipid subunit of Enterococcus hirae Na(+)-ATPase complex
Y Kakinuma1, S Kakinuma, K Takase
1Faculty of Pharmaceutical Sciences, Chiba University, Japan.
Biochemical and Biophysical Research Communications
|September 15, 1993
Summary
Researchers identified the ntpK gene in Enterococcus hirae, encoding a hydrophobic protein. This protein is the proteolipid component of Na(+)-transport ATPase and is similar to eukaryotic V-ATPases.
Area of Science:
- Biochemistry
- Molecular Biology
- Microbiology
Background:
- Enterococcus hirae possesses a Na(+)-transport ATPase crucial for cellular function.
- Previous studies identified major subunits of this enzyme.
Purpose of the Study:
- To further characterize the Na(+)-transport ATPase of Enterococcus hirae by sequencing its genome.
- To identify and analyze the gene encoding the proteolipid component of the enzyme.
Main Methods:
- Genome DNA sequencing of Enterococcus hirae.
- Gene cloning and sequence analysis.
- Protein purification and partial sequence analysis.
- Hydropathy profiling and sequence homology comparison.
Main Results:
- A novel gene, ntpK, was identified, encoding a 156-amino acid hydrophobic protein (16-kDa).
- The deduced amino acid sequence of the NtpK product matched the purified 16-kDa proteolipid of Na(+)-ATPase.
- The NtpK product exhibited significant sequence and hydropathy profile similarity to eukaryotic vacuolar (V-) H(+)-ATPase proteolipids.
- Homology between the N-terminal and C-terminal halves of the NtpK product suggested evolution via gene duplication.
Conclusions:
- The proteolipid component of Enterococcus hirae Na(+)-transport ATPase is encoded by the ntpK gene.
- This proteolipid shares significant homology with eukaryotic V-ATPase proteolipids, suggesting a common evolutionary origin.
- The findings indicate that the E. hirae Na(+)-ATPase proteolipid belongs to the eukaryotic V-ATPase family.