Table 3.

Synthetic lethality between Δpbp1a and ΔgpsB mutations in suppressed strains^a

Recipient strain	Genotype	Number of colonies at 20 h after transformation with Δpbp ampliconsb
		Δpbp1a	Δpbp1b	Δpbp2a
EL59	R6	>500	>500	>500
IU8224	R6 ΔgpsB	0	>500	>500
IU1945	D39 Δcps	>500	>300	>300
IU6442c	D39 Δcps ΔgpsB phpP(G229D)	0	>300	>300
IU9256	Rx1	>500	>500	>500
IU11574	Rx1 ΔgpsB	0	>500	>500
IU9262	Rx1 ΔgpsB phpP(L148S)	0	>500	>500

^aRecipient strains were constructed as described in Table S1. Transformations and visualization of colonies from 100 µL or 1 mL of transformation mixture were performed as described in Experimental procedures. Zeros (0) indicate no visible colonies after 40 h of incubation. The same results were obtained for each strain from two independent transformation experiments.

^bΔpbp1a::P_c-erm, Δpbp1b::P_c-erm, and Δpbp2a::P_c-erm amplicons with ≈ 1 kb flanking sequences were obtained from strains E177, E193, and E180 respectively (Table S1). Numbers of colonies indicated were obtained from 1 mL of transformation mixture.

^cControl transformations of a ΔgpsB<>aad9 amplicon into strains IU1824 (D39 Δcps rpsL1), IU6741 (IU1824 Δpbp1a), IU1945 (D39 Δcps), E180 (IU1945 Δpbp2a::P_c-erm), or E193 (IU1945 Δpbp1b::P_c-erm) resulted in 0 colonies in 20 h, indicating that D39 Δcps ΔgpsB Δpbp2a or ΔgpsB Δpbp1b strains are only viable when they contain the phpP(G229D) suppressor mutation.