TABLE 1.

Strains used in this work

Strain	Genotypea	Comments	Reference or source
RP437		Wild-type chemotaxis strain	55
ΔR	ΔcheR		Christopher Rao
ΔB	ΔcheB		Christopher Rao
CR20	CheY::FRT	Runner	Christopher Rao (56)
UU1250	Δ(tar-tap) Δtsr Δaer Δtrg	Receptorless strain	John S. Parkinson (25)
PS2001::pMS164	ΔcheB ΔcheY ΔcheZ	Lacks CheB, CheY, and CheZ and contains pMS164 plasmid	Philippe Cluzel (52)
UU1615	Δaer Δtar Δtap Δtrg	Tsr-only strain	John S. Parkinson (38)
UU1624	Δaer Δtsr Δtap Δtrg	Tar-only strain	John S. Parkinson (38)
UU1250::pSB20	Δ(tar-tap) Δtsr Δaer Δtrg	Aer-only strain; contains pSB20 plasmid	John S. Parkinson (7)
UU1250::pPA705	Δ(tar-tap) Δtsr Δaer Δtrg	Trg-only strain; contains pPA705 plasmid	This work
TP6	Δ(tar-tap) Δtsr Δaer Δtrg	Tap-only strain; contains pTP1 plasmid	This work
RP8604	Δtsr Δtrg	Tar-Aer-Tap strain	John S. Parkinson
RP1131	trg::Tn10	ΔTrg strain	John S. Parkinson
UU1117	Δaer	ΔAer strain	John S. Parkinson (57)
UU1623	Δtsr Δtrg Δtap	Tar-Aer strain	John S. Parkinson

^aFRT, flippase recombination target.