TABLE 2.

Effects of amino acid changes in CzcD and ZitB and corresponding positions in either protein

CzcDZitB
ChangeEffectIC50 of Zn2+ (μM)ab (μM)bChangeEffectIC50 of Zn2+ (μM)ab (μM)b
NoneWild-type CzcD204 ± 346NoneWild-type ZitB736 ± 114146
ControlNo CzcD108 ± 9c55ControlNo ZitB105 ± 48d114
ΔC terminuse,fΔC terminusNo function122 ± 5141
H5RPartially activeg163 ± 3038H3h
H7RNo function105 ± 138H5h
H9RPartially active154± 6542H7h
H49RNot expressedNDiH53RNo function241 ± 178108
H49ANo function104 ± 430H53h
H237RNo function118 ± 1836H243h
H251RNot expressedNDH256h
H251APartially active137 ± 1260H256h
H280RNot expressedNDH254h
H280ANo function93 ± 1540H284h
H298RNot expressedNDN302h
H298ANo function102 ± 745N302h
C290SHyperSensitivej78 ± 045C294SWild type554 ± 341117
E31DPartially active125 ± 736E35h
E31NNot expressedNDE35h
E31KNo function125 ± 731E35h
E154DNo function116 ± 1234H159ENo function173 ± 3473
E154NNo function100 ± 1331H159RNo function213 ± 69156
E209fE214ANo function90 ± 48183
D46fD50EPartially active209 ± 1972
D46fD50ANo function149 ± 1777
D53EHypersensitive60 ± 229D57h
D53AHypersensitive56 ± 647D57ANo function148 ± 1777
D53NHypersensitive48 ± 726D57h
D158ANo function85 ± 677D163ANo function192 ± 43101
D158ENo function112 ± 1922D163ENo function122 ± 29121
D181EHypersensitive76 ± 6156D186EPartially active210 ± 3375
D181NHypersensitive59 ± 119D186h
D181APartially active136 ± 8059D186ANo function102 ± 3486
M5OLHypersensitive63 ± 740M54LPartially active286 ± 9596
R108fR112AWild type744 ± 172172
N130fN135ANo function168 ± 2770
S162fS167ANo function127 ± 1945
F174fW182LPartially active201 ± 3168
W239fW245LPartially active461 ± 125103
  • a IC50, 50% inhibitory concentration (zinc concentration required to decrease the cell density of the growing culture to one-half the positive control value with no added zinc). Values are given with standard deviations.

  • b b is the slope of the sigmoidal dose-response curve.

  • c Value determined in Halle, Germany, for CzcD experiments.

  • d Value determined in Tuczon, Ariz., for ZitB experiments.

  • e ΔC terminus, deletion of the carboxy terminus.

  • f Site that was not changed in CzcD but was changed in ZitB.

  • g The phenotype was partially active if the IC50 of the wild type minus deviation was greater than the IC50 of the mutant plus deviation and the IC50 of the mutant minus deviation was less than the IC50 of the vector control plus deviation.

  • h Site that was changed in CzcD but was not changed in ZitB.

  • i ND, not determined.

  • j The phenotype was hypersensitive if the IC50 of the mutant plus deviation was less than the IC50 of the vector control minus deviation.