Fig. 4.
Mutation of His156 to Ala in AmtB (AmtBH156A) diminishes TFCDL binding and abolishes the allosteric effect for binding TFCDL and POPE. (A) Mass spectra for AmtBH156A with TFCDL, TFCDL and POPC, and TFCDL and POPE as labeled. (B) Zoomed regions for the AmtBH156A 15+ charge state illustrating reduced POPE and TFCDL binding compared with WT AmtB. The mole ratio of TFCDL to AmtBH156A is 3:1. POPC and POPE were analyzed at a mole ratio of 1.5 and 1 to AmtB, respectively. Shown as described in Fig. 2B.