Table 1.

Host strain and Cas9/dCas9 expression construct for each screening experiment

Screening experimenta	Host	Cas9/dCas9 expression vector
Cas9 (selective)	WTb	pCas9-J23109c
Cas9 (ΔrecA) (selective)	ΔrecA	pCas9-J23109
dCas9 (control)	WT	pdCas9-J23109
eSpCas9 (selective)	WT	peSpCas9-J23113c
eSpdCas9 (control)	WT	peSpdCas9-J23113

^aScreening experiment dCas9 is the negative control for Cas9 and Cas9 (ΔrecA); eSpdCas9 is the negative control for eSpCas9.

^bWT: E. coli strain MCm (E. coli K12 MG1655 smf::cat, see online Methods).

^cJ23109 is a moderate-strength promoter, and J23113 is of weak strength.