Table 6.
Summary of reactive His(HK)-to-Asp(RR) distances in reported TCS protein complexes.
| Group (based on distance discriminants*) | Complex partners (N° complexes per ASU†) | Distance his(Nε2)-Asp(Oδ1) (Å)‡ | Reaction coordinate distance (Å)§ | Distance ratio [Mg2+-Asp(Oδ1)/Mg2+-His(Nε2)] | Pdb (ID) | Phosphotransfer reaction direction | Remarks | |
|---|---|---|---|---|---|---|---|---|
| Phosphorelays | I |
Spo0F:Spo0B¶
(4) |
5.7; 5.3; 5.1; 5.1 | 4.1; 3.8; 3.6; 3.5 | 0.82; 0.74; 0.65; 0.67 | 2FTK | P~Asp(Spo0F)→ His(Spo0B) | Spo0B bears a DHp domain |
|
SLN1:YPD1**
(1) |
4.9 | 3.2 | 0.67 | 2R25 | P~Asp(SLN1)→ His(YPD1) | YPD1 bears an HPt domain | ||
|
AHK5:AHP1††
(1) |
6.4 | ND[8] | 0.72 | 4EUK | P~Asp(AHK5-REC)→ His(AHP1) | AHP1 bears an HPt domain | ||
|
ChpT:CtrA§§
(2) |
5.9¶¶ | ND‡‡ | 0.64*** | 4QPJ | P~His(ChptA)→ Asp(CtrA) | ChpT bears a DHp domain P~Asp(CtrA)→His(ChptA) remains to be confirmed |
||
| HKs undergoing auto-phosphorylation | I |
CpxA:ATP †††
(1) |
5.0‡‡‡ | 3.4 | 0.82 | 4BIW | ATP→His(CpxA) | AMP-PCP was used as non-hydrolizable ATP analogs (between phosphates β and γ there is a C atom substituting the O) |
|
HK853/EnvZ chimera:ATP14
(1) |
5.3‡‡‡ | 3.6 | 0.72 | 4KP4 | ATP→His(HK853) | |||
| RR-mediated phosphorylation of imidazole | I |
Imidazole:CheY¶¶¶
(2) |
5.1; 5.1 | 3.3; 3.3 | 0.71; 0.73 | 5DKF | P~AspCheY) → imidazole | In vitro engineering of a phosphorelaying system from CheY to PhoR, using imidazole as a rudimentary HPt |
| HK:RR complexes | II |
HK853:RR468****
(2) |
7.6; 8.0†††† | 5.7; 6.1 †††† | 0.51; 0.48†††† | 3DGE | P~His(HK853)→ Asp(RR468) | HK:RR complex, snapshot of the phosphatase state according to the authors. |
|
DesK:DesR‡‡‡‡
(2) |
7.6§§§§ | 5.8§§§§ | 0.47§§§§ | 5IUK | P~His(DesK)→ Asp(DesR) | HK:RR complex in the phosphotransferase state | ||
|
CheA3:CheY6¶¶¶¶
(1) |
7.3 | ND‡‡ | 0.52***** | 3KYJ | P~His(CheA3)→ Asp(CheY6) | 3KYJ is not phosphorylated on either partner; 3KYI with P-His on CheA3 displays an unproductive P~His rotamer, otherwise confirming 3KYJ’s 3D organization |
* Distance between reactive His(Nε2)-Asp(Oδ1) less than or greater than 6.5Å, and distance ratio [Mg2+-Asp(Oδ1) / Mg2+-His(Nε2)] less than or greater than 0.6.
† ASU = asymmetric unit.
‡ Each distance corresponds to the one measured in each one of the independently refined complexes in the ASU.
§ Distances are reported in the same order as in the previous column, with correspondence among same individual complexes.
¶ Bacillus subtilis (Varughese et al.,2006).
** Saccharomyces cerevisiae (Zhao et al., 2008).
††Arabidopsis thaliana (Bauer et al., 2013).
‡‡ Not determined : no phosphoryl group or phosphoryl-mimetic present in the structure.
§§ Brucella abortus (Willett et al., 2015).
¶¶ Only one of the two complexes in the ASU (ChpTchainA:CtrAchainC, display the reactive His and Asp properly oriented poised for reacting. Only one distance is thus recorded.
*** No Mg2+ cation was actually bound on CtrA. A metal atom was modeled by superimposing the structure of RR468 with bound BeF3 (PDB 3GL9), one of the top ranking structures in multiple structural alignments with CtrA (DALI Z score 12.9, rmsd 0.8Å superimposing 98 αCs).
††† Escherichia coli (Mechaly et al., 2014).
‡‡‡ In the autophosphorylation complexes the distance is recorded between His(Nε2) and the position of the O between phosphates β and γ.
§§§ Thermotoga maritima (HK853) / E. coli (EnvZ) (Casino et al., 2014).
¶¶¶ E. coli (Page et al., 2015).
**** Thermotoga maritima (Casino et al., 2009).
†††† These distances have been calculated by superimposing the phosphorylation-mimetic structure of RR468 alone with bound BeF3 (PDB 3GL9), onto 3DGE, in order to use better estimations of the receiver Asp position as well as of the phosphorus atom.
‡‡‡‡B. subtilis, this report.
§§§§ Glu188 present in the crystal structure was substituted by wt P~His following superposition of wt phosphorylated DesKC (PDB 5IUM) onto one of the phosphotransferase DesKCH188E:DesR-REC complexes in the ASU (chains A-B:E). Distances are reported after energy minimization. See Materials and methods.
¶¶¶¶ Rhodobacter sphaeroides (Bell et al., 2010).
***** The position of Mg2+ cation was modeled using PDB 4TMY as template.