TABLE 2.

Measure of competitive inhibition in A. tumefaciens strains with 100 nM 3-oxo-C₈-HSL

Inhibitor	β-Galactosidase activity ina:
	WCF47(pCF372) with analog at concn (nM):			WCF47(pCF372)(pCF218) with analog at concn (nM):
	102	103	104	102	103	104
None	340	NA	NA	1,400	NA	NA
A	360	250	150	1,600	1,300	1,200
B	350	240	110	1,500	1,500	1,300
C	340	11	0.9	1,600	1,500	1,200
D	210	120	470	1,500	1,500	1,100
F	280	38	74	1,300	1,200	1,000
G	250	200	180	1,400	1,400	1,000
H	360	320	17	1,800	1,500	850
I	400	330	380	1,400	840	1,300
J	350	350	97	1,600	1,600	1,200
K	380	340	46	1,500	1,600	940
L	180	19	2.4	1,400	1,200	950
M	95	6.0	5.7	1,600	1,500	1,200
N	370	93	2.6	1,400	1,300	1,100
O	410	330	17	1,600	1,400	1,500
P	220	9.5	3.6	1,500	1,500	1,300
Q	350	99	1.9	1,400	1,400	1,000
R	320	330	330	1,600	1,600	1,500
S	380	320	260	1,600	1,600	1,400
T	330	320	76	1,400	1,600	890
U	340	170	3.9	1,500	1,300	1,100
V	370	250	8.6	1,500	1,500	780
W	360	360	140	1,400	1,300	1,100
X	340	330	310	1,500	990	1,300
Y	360	350	340	1,600	930	1,700
Z	370	390	300	1,600	1,100	1,500
AA	320	370	210	1,300	1,500	1,100
AB	230	48	33	1,300	1,400	940
AC	380	370	300	1,400	1,500	950
AD	340	310	270	1,600	1,200	1,500
AE	340	220	13	1,600	1,500	970
AF	360	350	320	1,600	1,500	970
AG	370	350	64	1,400	1,100	1,000

^aThe indicated analogs were provided at the noted concentrations to cultures of WCF47(pCF372) containing or lacking pCF218 in AT broth supplemented with 2 mg of opine per ml. Bacteria were cultured for 12 h and assayed for β-galactosidase specific activity (29). β-Galactosidase expression in the absence of autoinducers was less than 2 Miller units. NA, not applicable.