TABLE 1.

Examples of cytoplasmic sensor proteins for monoaromatic compounds^a

Substrate(s)	Sensor	Family	Sensory domain(s)	Bacterium	Reference
Alkylbenzenes
Tolueneb	TdiS	Two component	PAS (2×)	Aromatoleum aromaticum EbN1	15
Toluenec	TodS	Two component	PAS (2×)	Pseudomonas putida F1	28
Toluenec	TmoS	Two component	PAS (2×)	Pseudomonas mendocina	72
Toluenec , xylenec	XylR	XylR/DmpRd	4VR	Pseudomonas putida mt-2	22
Ethylbenzeneb	Tcs2	Two component	PAS (2×)	Aromatoleum aromaticum EbN1	15
Styrenec	StyS	Two component	PAS (2×)	Pseudomonas putida Y2	73
Alkylphenols
Phenolb	PdeR	XylR/DmpRd	XylR, 4VR	Aromatoleum aromaticum EbN1	15
Phenolc; o-, m-, and p-cresolc; 2,3-, 2,4-, 2,5-, and 3,4-dimethylphenolc	DmpR	XylR/DmpRd	4VR	Pseudomonas sp. strain CF600	25
p-Ethylphenolb ; p-hydroxyacetophenoneb	EtpR	XylR/DmpRd	XylR, 4VR	Aromatoleum aromaticum EbN1	18
p-Cresolb	PcrS	Two component	XylR, 4VR, PAS (2×)	Aromatoleum aromaticum EbN1	15
Aromatic ketones and carboxylates
Acetophenoneb	Tcs1	Two component	PAS	Aromatoleum aromaticum EbN1	15
Benzoatec; 2- and 3-methyl-, 2,3-, 2,5-, and 3,4-dimethylbenzoatec	XylS	AraC/XylSd	AraC	Pseudomonas putida	23
p-Hydroxybenzoate	PobR	AraC/XylSd	AraC	Azotobacter chroococcum	74
Salicylatec	NahR	LysRd	LysR	Pseudomonas putida	75
Protocatechuatec	PcaU	IclRd	GAF	Acinetobacter sp. strain ADP1	76

^aCytoplasmic localization was assessed using the programs SignalP (signal peptide prediction) and TMHMM (prediction of transmembrane helices). Transmembrane-spanning histidine kinases PhoQ of E. coli (77) and BpdS of Rhodococcus sp. strain M5 (78) served as controls.

^bEffector functionality predicted.

^cEffector functionality proven.

^dOne-component system.