Non-bilayer structures in mitochondrial membranes regulate ATP synthase activity.

Cardiolipin (CL) is an anionic phospholipid at the inner mitochondrial membrane (IMM) that facilitates the formation of transient non-bilayer (non-lamellar) structures to maintain mitochondrial integrity. CL modulates mitochondrial functions including ATP synthesis. However, the biophysical mechanisms by which CL generates non-lamellar structures and the extent to which these structures contribute to ATP synthesis remain unknown.

A site-specific endonuclease from the thermophilic strain Bacillus species F4.

A strain producing the site-specific endonuclease BspF4I was found during screening of thermophilic bacteria isolated from soil. The restriction endonuclease, free from contaminant nonspecific nucleases, was purified using three steps of column chromatography--on hydroxyapatite, blue agarose, and DEAE-Trisacryl. The enzyme is stable on storage and exhibits maximal activity at 48-56 degrees C in the presence of albumin in buffer containing 10 mM Tris-HCl (pH 7.