Role of a-Subunit VISIT-DG Sequence Residues Ile-346 and Ile-348 in the Catalytic Sites of Escherichia Coli ATP Synthase.

F1FO-ATP synthase is the primary source of cellular energy production in most living organisms. Malfunction of this enzyme is implicated in diseases. There are many functional motifs in and around the catalytic sites of this enzyme. One of them is the highly conserved α-subunit VISIT-DG sequence that is close to the Pi binding subdomain. The questions arise Are they involved in Pi binding? Or are they there simply for the structural integrity of the catalytic sites? Here, αIle-346and αIle-348, two important residues of the conserved VISIT-DG sequence, are discussed. Each residue was mutated to A/R/D/Q. Growth assays in limiting glucose media and on succinate plates suggests αIle-346 and αIle-348 are critical for the normal enzymatic function (oxidative phosphorylation). And the biochemical assays do suggest both αI-346 and αI-348 are required to maintain catalytic site, involved in Pi binding indirectly, but αI-348 plays more important role than αI-346