Thursday, July 29, 2010

16th EBEC: short notes

One of the most exciting ATP synthase news on the EBEC conference(Warsaw, July 17-22) was a new structure of bovine F1+c-oligomer structure that had eight c-subunits in the c-ring (John Walker's talk). John also pointed out that since the sequence of mammalian (and avian, as far as I can remember) c-subunit is identical for all organism sequenced so far, it is highly probable that c8 is the stoichiometry for all mammals (and birds?). This also suggests that their H+/ATP ratio is 2.67.

Other things:

A crystal structure of bovine F1 grown in the presence of phosphonate had ADP bound in all 3 catalytic sites, but the low affinity site lacks Mg2+ (John Walker's group). Does Mg2+ dissociate before nucleotide?

Another new structure - thermoalkaliphilic Caldalkalibacillus thermarum F1 at 3 Å resolution (Greg Cook in collaboration with John Walker) crystallized in the presence of ADP. Unlike the previous structure where all three catalytic sites were empty and that had a curved subunit gamma, the new structure is pretty similar to bovine ones, suggesting that deformation of gamma in the first structure was due to crystallization conditions. In the new structure one can also see an ATP molecule bound to the epsilon subunit. Since no ATP was added to the crystallization mix, it seems that the nucleotide binding site on C. thermarum epsilon is highly selective at room temperature: usually the ATP contamination in commercial ADP does not exceed 0.5%.

Toshiharu Suziki from Masasuke Yoshida's lab succeeded in expressing human F1 in E. coli and characterized its rotation at single-molecule level. This opens a way to study the effects of mutations on mitochondrial F1 activity.

Ryota Iino from Hiroyuki Noji's lab reported clearly distinguishable 36o rotation steps in E. coli ATP synthase with mutation aE219H introduced to slow the rotation in FO.

For the rest of ATP synthase EBEC reports take a look in the special BBA Bioenergetics issue with 16th EBEC Proceedings for full-text papers and in the volume supplement with poster abstracts.