(i) An N-terminal domain of signal perception (sensor) that
can be periplasmic or bound to the cytoplasmic membrane (Table 9.3., Mascher et al. 2006)
(ii) A conserved C-terminal cytoplasmic region that
includes a dimerization domain with two α helices
(HisKA/DHp) containing the phosphorylation site,
which is a highly conserved histidine residue and the
catalytic domain that has a kinase activity (HATPase_c)
The periplasmic domains of membrane HK (EnvZ) are
poorly conserved which could reflect specific sensor types
for given stimuli. Conversely, the cytoplasmic sensor HK
that can be anchored to the membrane (ArcB) or soluble
(KinA) often has a conserved GAF or PAS domain, a domain
sensitive to changes in redox potential, in O 2 concentration, or
in light intensity, and varies also as a function of the prosthetic
group, heme, or FAD chromophore linked to the PAS domain.
Table 9.1 Distribution of different signaling systems in the prokaryotic world
Total number of proteins HK MCP STYK GGDEF/EAL/HD-GYP AC RR Total
Bacteria
Actinobacteria
Frankia alni
6,787
45 –
59
9
3
49
179
Mycobacterium tuberculosis
3,927
13 –
13
2
16
13
57
Streptomyces coelicolor
8,154
95 –
37
8
1
84
225
Cyanobacteria
Nostoc sp. PCC7120
6,033
134 3
52
17
6
96
286
Synechocystis sp. PCC 6,803
3,567
46 4
12
28
3
47
128
Alphaproteobacteria
Agrobacterium tumefaciens
5,402
53 20
2
29
3
58
162
Bradyrhizobium japonicum
8,317
92 35
4
42
35
96
298
Caulobacter crescentus
3,737
62 18
2
14
3
45
142
Rhodopseudomonas palustris
4,813
66 29
5
42
7
54
197
Rickettsia prowazekii
835
4 –
1
2
–
4
10
Wolbachia (Drosophila endosymbiont) 1,195
2 –
1
1
–
2
5
Betaproteobacteria
Bordetella pertussis
3,436
18 5
3
9
–
29
57
Dechloromonas aromatica
4,171
103 25
9
75
3
98
292
Gammaproteobacteria
Alcanivorax borkumensis
2,755
30 1
6
13
2
31
81
Escherichia coli K12
4,242
30 5
12
29
1
32
99
Pseudomonas aeruginosa
5,567
63 26
8
41
2
73
206
Salmonella enterica
4,758
30 6
3
21
1
32
93
Vibrio cholerae
3,835
43 45
1
62
1
49
196
Deltaproteobacteria
Desulfovibrio vulgaris
3,531
64 28
1
41
1
76
200
Geobacter sulfurreducens
3,446
92 33
1
39
–
91
240
Epsilonproteobacteria
Wolinella succinogenes
2,044
39 31
2
26
1
48
138
Firmicutes
Bacillus subtilis
4,105
36 10
4
6
–
35
91
Clostridium acetobutylicum
3,848
37 38
5
20
1
43
144
Mycoplasma pneumoniae
689
–
–
1
–
–
–
1
Staphylococcus aureus
2,624
17 –
2
1
–
17
37
Spirochaetes
Treponema denticola
2,767
7 20
–
13
9
11
59
Archaea
Sulfolobus acidocaldarius
2,223
–
–
10
–
1
–
11
Haloarcula marismortui
4,240
59 17
8
–
1
25
109
Methanospirillum hungatei
3,139
76 27
9
–
1
61
169
Modified after Galperin (2005) http://www.ncbi.nlm.nih.gov/Complete_Genomes/SignalCensus.html
HK histidine protein kinase, MCP methyl-accepting chemotaxis proteins, STYK Ser/Thr/Tyr kinase, GGDEF, EAL, HD-GYP proteins involved in
the metabolism of di-cGMP, AC adenylate cyclase involved in the metabolism of cAMP, RR response regulator
300
P. Normand et al.
can be periplasmic or bound to the cytoplasmic membrane (Table 9.3., Mascher et al. 2006)
(ii) A conserved C-terminal cytoplasmic region that
includes a dimerization domain with two α helices
(HisKA/DHp) containing the phosphorylation site,
which is a highly conserved histidine residue and the
catalytic domain that has a kinase activity (HATPase_c)
The periplasmic domains of membrane HK (EnvZ) are
poorly conserved which could reflect specific sensor types
for given stimuli. Conversely, the cytoplasmic sensor HK
that can be anchored to the membrane (ArcB) or soluble
(KinA) often has a conserved GAF or PAS domain, a domain
sensitive to changes in redox potential, in O 2 concentration, or
in light intensity, and varies also as a function of the prosthetic
group, heme, or FAD chromophore linked to the PAS domain.
Table 9.1 Distribution of different signaling systems in the prokaryotic world
Total number of proteins HK MCP STYK GGDEF/EAL/HD-GYP AC RR Total
Bacteria
Actinobacteria
Frankia alni
6,787
45 –
59
9
3
49
179
Mycobacterium tuberculosis
3,927
13 –
13
2
16
13
57
Streptomyces coelicolor
8,154
95 –
37
8
1
84
225
Cyanobacteria
Nostoc sp. PCC7120
6,033
134 3
52
17
6
96
286
Synechocystis sp. PCC 6,803
3,567
46 4
12
28
3
47
128
Alphaproteobacteria
Agrobacterium tumefaciens
5,402
53 20
2
29
3
58
162
Bradyrhizobium japonicum
8,317
92 35
4
42
35
96
298
Caulobacter crescentus
3,737
62 18
2
14
3
45
142
Rhodopseudomonas palustris
4,813
66 29
5
42
7
54
197
Rickettsia prowazekii
835
4 –
1
2
–
4
10
Wolbachia (Drosophila endosymbiont) 1,195
2 –
1
1
–
2
5
Betaproteobacteria
Bordetella pertussis
3,436
18 5
3
9
–
29
57
Dechloromonas aromatica
4,171
103 25
9
75
3
98
292
Gammaproteobacteria
Alcanivorax borkumensis
2,755
30 1
6
13
2
31
81
Escherichia coli K12
4,242
30 5
12
29
1
32
99
Pseudomonas aeruginosa
5,567
63 26
8
41
2
73
206
Salmonella enterica
4,758
30 6
3
21
1
32
93
Vibrio cholerae
3,835
43 45
1
62
1
49
196
Deltaproteobacteria
Desulfovibrio vulgaris
3,531
64 28
1
41
1
76
200
Geobacter sulfurreducens
3,446
92 33
1
39
–
91
240
Epsilonproteobacteria
Wolinella succinogenes
2,044
39 31
2
26
1
48
138
Firmicutes
Bacillus subtilis
4,105
36 10
4
6
–
35
91
Clostridium acetobutylicum
3,848
37 38
5
20
1
43
144
Mycoplasma pneumoniae
689
–
–
1
–
–
–
1
Staphylococcus aureus
2,624
17 –
2
1
–
17
37
Spirochaetes
Treponema denticola
2,767
7 20
–
13
9
11
59
Archaea
Sulfolobus acidocaldarius
2,223
–
–
10
–
1
–
11
Haloarcula marismortui
4,240
59 17
8
–
1
25
109
Methanospirillum hungatei
3,139
76 27
9
–
1
61
169
Modified after Galperin (2005) http://www.ncbi.nlm.nih.gov/Complete_Genomes/SignalCensus.html
HK histidine protein kinase, MCP methyl-accepting chemotaxis proteins, STYK Ser/Thr/Tyr kinase, GGDEF, EAL, HD-GYP proteins involved in
the metabolism of di-cGMP, AC adenylate cyclase involved in the metabolism of cAMP, RR response regulator
300
P. Normand et al.