1: J Biol Chem  2001 Jul 6;276(27):25480-6 

Purine but not pyrimidine nucleotides support rotation of F(1)-ATPase.

Noji H, Bald D, Yasuda R, Itoh H, Yoshida M, Kinosita K Jr.

CREST "Genetic Programming" Team 13, Teikyo University Biotechnology Research
Center 3F, Nogawa 907, Miyamae-ku, Kawasaki 216-0001, Japan.

The binding change model for the F(1)-ATPase predicts that its rotation is
intimately correlated with the changes in the affinities of the three catalytic
sites for nucleotides. If so, subtle differences in the nucleotide structure may
have pronounced effects on rotation. Here we show by single-molecule imaging
that purine nucleotides ATP, GTP, and ITP support rotation but pyrimidine
nucleotides UTP and CTP do not, suggesting that the extra ring in purine is
indispensable for proper operation of this molecular motor. Although the three
purine nucleotides were bound to the enzyme at different rates, all showed
similar rotational characteristics: counterclockwise rotation, 120 degrees steps
each driven by hydrolysis of one nucleotide molecule, occasional back steps,
rotary torque of approximately 40 piconewtons (pN).nm, and mechanical work done
in a step of approximately 80 pN.nm. These latter characteristics are likely to
be determined by the rotational mechanism built in the protein structure, which
purine nucleotides can energize. With ATP and GTP, rotation was observed even
when the free energy of hydrolysis was -80 pN.nm/molecule, indicating
approximately 100% efficiency. Reconstituted F(o)F(1)-ATPase actively
translocated protons by hydrolyzing ATP, GTP, and ITP, but CTP and UTP were not
even hydrolyzed. Isolated F(1) very slowly hydrolyzed UTP (but not CTP),
suggesting possible uncoupling from rotation.

PMID: 11279248 [PubMed - indexed for MEDLINE]