The α-subunit of Escherichia coli F1-ATPase contains an adenine-specific noncatalytic nucleotide-binding domain. A recent proposal (Maggio, M.B., Pagan, J., Parsonage, D., Hatch, L., and Senior, A.E. (1987) J. Biol. Chem. 262, 8981-8984) suggested that this domain is formed by residues 160-340, approximately, in α-subunit. Within this proposed domain is a sequence Gly-X-X-X-X-Gly-Lys which is conserved in a large and diverse group of nucleotide-binding proteins and is thought to interact with phosphate groups of bound nucleotide. In this work, residue αLys-175, the terminal residue of the above conserved sequence in F1-α-subunit, was mutagenized to Ile or Glu. The specific activity of purified mutant F1-ATPase was reduced by 2.5-fold (Ile) or 3-fold (Glu). Apparent binding of ATP to α-subunit, as measured by the centrifuge column procedure, was strongly impaired and ATP-induced conformational change in α-subunit, as measured by protection against trypsin proteolysis, was nearly abolished in both mutants. The results suggest that residue αLys-175 is located within the nucleotide-binding domain of α-subunit, and that this residue is functionally involved in nucleotide binding. The results support previous suggestions that the α-subunit nucleotide-binding site is not involved, directly or indirectly, in catalysis.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Biological Chemistry|
|State||Published - 1988|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology