Table 1. Two component systems (TS) identified in the genomes of AOA representatives from the group I.1a, I.1b and AOB using Conserved Domain Search and TIGRfam database.

Stimulus or related function	TS gene	Group I.1b		Group I.1a			AOB
		N. everg.	N. garg.	N. kor.	N. lim.	N. marit.	N. europaea
Cell-envelope stress	BaeS	17	20	8	11	4	6
	BaeR	0	0	0	0	0	0
Levels of phosphate	PhoR	0(12)*	0(14)	0(6)	0(6)	0(1)	0(5)
	PhoP(PhoB)	18(3)	21(7)	8(5)	9(9)	11(4)	4(8)
	PhoU	18(4)	13(5)	9(3)	10(3)	7(2)	4(1)
Chemotaxis	CheA	2	2	0	0	0	3
	CheB	2	1	0	1	0	2
	CheC	2	1	0	1	0	0
	CheY	5	3	0	1	1	3
	CheR	0	2	0	3	0	0
	CheX	1	0	0	1	0	0
Nitrogen levels	NtrC	1(14)	0(24)	0(8)	0(17)	0(6)	1(7)
	GlnK	4	4	2	2	2	0
	NtrB	1(2)	0(2)	0(1)	0	0(1)	1(3)
Osmotic stress	EnvZ	0	0	0	0	0	0
	OmpR	1	1	1	0	0	5
Osmotic stress	MtrB	0	0	0	0	0	0
	MtrA	0(1)	0(1)	0(1)	0(1)	0(1)	0
Trimethylamine N-oxide as an alternate electron acceptor	TorS	0(6)	0(7)	0	0(4)	0(4)	0(2)
	TorR	0	0	0	0	0	0
Oxidative, weak acid, and osmotic stress	BarA	0	0	0	0	0	0
	SirA	1	1	1	1	1	2
Copper resistance (CopRS)	CopS	0	0(1)	0(1)	0(5)	0(6)	0(5)
	CopR	0(2)	0(3)	0(2)	0(2)	0	0(4)
Quorum sensing	ComP	0	0	0	0	0	0
	ComA	0(2)	0(2)	0	0	0	0
Pyruvate response	YpdA	0(4)	0(6)	0(3)	0(3)	0(3)	0(10)
	YpdB	0	0	0	0	0	0
	Total	69(52)	70(72)	27(30)	26(50)	26(28)	24(45)

* components of TS found by TIGRfam database.