Table 1.

Catalytic properties of Tn3 resolvase variants in E. coli and in vitro

		In vivo recombination		In vitro recombination
Mutant	Mutations	res × res	l × l	res × res	l × l	Site I synapsis
WT	Wild-type	++	−	++	−	−
N	R2A E56K	−	−	−	−	−
S	G101S	++	−	ND	ND	ND
Y	D102Y	++	−	++	−	−
Q	E124Q	++	−	++	−	−
SY	G101S D102Y	++	++	++	+	−
YQ	D102Y E124Q	++	+	++	+	−
NYQ	R2A E56K D102Y E124Q	++	++	+	+	−
NSY	R2A E56K G101S D102Y	++	++	++	+	−
NSYQ	R2A E56K G101S D102Y E124Q	++	++	++	++	+
M	G101S D102Y M103I Q105L	++	+	++	++	+
MQ	G101S D102Y M103I Q105L E124Q	++	−	++	++	+
NM	R2A E56K G101S D102Y M103I Q105L	++	++	++	++	+
NMQ	NM + E124Q	++	+	++	++	+
C	A117V R121K E124Q	−	−	+	−	−
YC	D102Y A117V R121K E124Q	++	−	+	+	−
MC	M + C	−	−	+	+	ND

Recombination activity in E. coli was estimated by an assay for resolution as detected by colony colour (13). The results [taken from (13)] are shown as ++ (pale colonies, full resolution), + (pink colonies, partial resolution) or − (red colonies, low or zero resolution). In vitro assays were performed under standard conditions, using the substrates pMA21 (res × res) and pAL225 (site I × site I), as described in the Materials and methods section. The symbols give a rough comparison of extent of recombination, high levels (such as wild-type resolvase on pMA21, or NM resolvase on pAL225) shown as ++, lower levels as + and no observable recombination as −. ND indicates ‘not done’. Synapsis assays used non-denaturing TBE gels as described in Materials and methods section; + indicates the observation of a distinct site I synapse band.