Comparison of "Qo-site occupancy" (as judged by gx=1.80 signal) with activity and inhibitor resistance for cytochrome b mutants

                                        gx              activity        Myx             Stig
Residue (Rhodobact. mutant)     peak at  size                        (resistant or (hyper sens))

(Data from Ding et al., 1-4 and Brasseur et al., 5)
M125    (M140R)                 (normal)                none (ps-)      I,S             I,(L,N,D)
F129    (F144S,V)               (partially occ)         moderate QH2ox  I,G,L,N         I,G,L
        (F144N,I)               (low occupancy)         slow QH2ox      S,A             Y
        (F144G,L)               (empty)                 slow QH2ox
        (F144H)                 (normal)                moderate QH2ox
        (F144K)                 (normal, peak changed)  slow QH2ox
        (F144R)                 (normal, peak changed)  none
G131    (G146A,V)               (empty)                 none (ps-)
Y132    (Y147A,S)               (normal)                none (ps-)      V,F
G137    (G152R)                 (normal)                none            T,D,E,H,R,K,C,Y,I,F,L,V,N
G143    (G158A)                 (normal)                fast
        (G158S)                 (partially occ)         moderate
        (G158W)                 (empty)                 very slow
        (G158V,L,I,C,N)         (empty)                 none
T145    (T160F)                 (empty)                 slow (ps-)
T145    (T160R,S,C,L,Y)         (partially occ)         slow            (R,S,C,L,Y)
T148    (T163R)                 (empty)                 v.slow          (V,L,I)         A,C

(Data from Barquera et al. (in preparation), and see ref. 6)
P187    (P202L)                 1.80    medium          fast            
P187    (P202L, stig)           1.783   medium
N256    (N279Y)                 1.80    large           moderate        Y,K,I           Y,K,I
I269    (I292F)                 1.78    small           none (ps-)
P271    (P294L)                 1.77    v.small         none (ps-)
P271    (P294L, stig)           1.80    medium
        (P294S)                 1.80    large           moderate
E272    (E295Q)                 1.81    large           v. slow                         D,Q
        (E295G)                 1.80    large           slow
L282    (L305D)                 1.77    small           slow
        (L305A)                                         ps-
K288    (K329G)                 1.77    v.small         moderate
        (K329A                                          ps-
G291    (G332S)                                         moderate
        (G332I)                 1.77    medium          none (ps-)
        (G332D)                 1.77    small           moderate
Notes:                gx
                peak at  size
normal =        1.80    large
empty  =        1.77    small
partially occ = 30-40% normal
low occupancy = 20-25% normal

References

  1. Ding, H., Robertson, D.E., Daldal, F., and Dutton, P.L. (1992) Biochemistry 31, 3144-3158.
  2. Ding, H., Moser, C.C., Robertson, D.E., Tokito, M.K., Daldal, F., and Dutton, P.L. (1995) Biochemistry 34, 15979-15996.
  3. Ding, H., Daldal, F., and Dutton, P.L. (1995) Biochemistry 34, 15997-16003
  4. Saribas, A.S., Ding, H.G., Dutton, P.L., and Daldal, F. (1997) Biochim. Biophys. Acta 1319, 99-108
  5. Brasseur, G., Sami Saribas, A., and Daldal, F. (1996) Biochim. Biophys. Acta 1275, 61-69
  6. Crofts, A.R., Barquera, B., Bechmann, G., Guergova, M, Salcedo-Hernandez, R., Hacker, B., Hong, S., and Gennis, R.B. (1995) In Photosynthesis: from light to biosphere. (Mathis, P., ed.), Vol. II, pp. 493-500. Kluwer Academic Publ., Dordrecht