The Open Protein Structure Annotation Network
PDB Keyword


    Title Crystal structure of Chemotaxis protein CheX (YP_386777.1) from DESULFOVIBRIO DESULFURICANS G20 at 1.30 A resolution. To be published
    Site JCSG
    PDB Id 3hm4 Target Id 394179
    Molecular Characteristics
    Source Desulfovibrio desulfuricans g20
    Alias Ids TPS25781,YP_386777.1, _0037.001839_, 325441 Molecular Weight 16164.74 Da.
    Residues 155 Isoelectric Point 6.05
    Sequence msssgieiakpfvtattnvlstmagiqpipgqpyvkknnvakgdvsavvgitghkngsisvtftkqcai avvkamlgddiqdiiqdtkdavgevtnmisgqaraalsemgmtfqgatpsvimgdghtishvtkspvia ipfktnhgeftvefcle
      BLAST   FFAS

    Structure Determination
    Method XRAY Chains 2
    Resolution (Å) 1.30 Rfree 0.165
    Matthews' coefficent 1.97 Rfactor 0.138
    Waters 312 Solvent Content 37.60

    Ligand Information



    Protein Summary

    Gene Dde_0281 from Desulfovibrio desulfuricans g20 encodes the YP_386777 protein.  YP_386777.1 is a chemotaxis protein CheX (PF04509) that has been shown to act as a CheY-P phosphatase  (Muff 2007). The consensus sequence previously identified as the CheX putative active site is also present in this protein (DavgEvtNmisgqaraalsemgmtfqgatP).

    Bacterial chemotaxis involves the regulation of motility by a modified two-component signal transduction system. In the extensively studied Escherichia coli chemotaxis system, CheX is the phosphatase of the response regulator CheY-P (Zhao 2002). The proteins CheC, FliY, and CheX have been shown to comprise a novel family of CheY-P phosphatases found in the Archaea, Firmicutes, and various other bacteria (Szurmant 2004). This family of phosphatases share a consensus sequence (D/S-X3-E-X2-N-X21/22-P) (Szurmant 2004b) with four conserved residues thought to form the phosphatase active site (Park 2004).

    SCOP classifies 3hm4 in alpha+beta class, CheC-like (super)family. DALI provides top hits with other CheX proteins like 3h4y (Z-scr=27), 3h2d (Z-scr=23), 3iic (Z-scr=23), 1xko (Z-scr=20), 1squ (Z-scr=20). The 3hm4 monomer structure, shown below, has an alpha+beta fold with three helices on one side of a beta-sheet.


    The conserved consensus residues are shown below.


    The protein most likely forms a dimer in solution based on the crystal structure, as shown below.


    The top BLAST search hits are:

                                                                                                             Score    E
    Sequences producing significant alignments:                                    (bits) Value

    ref|YP_386777.1| chemotaxis protein CheX, putative [Desulfovibri...   291   1e-77
    ref|YP_009526.1| chemotaxis protein CheX, putative [Desulfovibri...   260   3e-68
    ref|YP_002436229.1| chemotaxis protein CheX, putative [Desulfovi...   249   6e-65
    ref|ZP_03466340.1| chemotaxis protein CheX, putative [Desulfovib...   196   5e-49
    ref|ZP_03466102.1| chemotaxis protein CheX, putative [Desulfovib...   191   2e-47
    ref|YP_002604959.1| CheX2 [Desulfobacterium autotrophicum HRM2] ...   159   8e-38
    ref|YP_002429472.1| CheC domain protein [Desulfatibacillum alken...   157   2e-37
    ref|YP_387692.1| chemotaxis protein CheX, putative [Desulfovibri...   148   2e-34

    3HM4 DALI Structural Similarity Search
    1 1xko 20.9 2.0 151 159 21 CHEMOTAXIS PROTEIN CHEX
    2 1squ 20.8 2.1 150 152 21 CHEX PROTEIN
    3 2f9z 12.2 2.9 144 190 11 CHEMOTAXIS PROTEIN CHEC
    4 1xkr 12.1 2.8 144 205 12 CHEMOTAXIS PROTEIN CHEC
    5 2hp7 10.1 3.0 134 179 7 FLAGELLAR MOTOR SWITCH PROTEIN FLIM


    An examination of these structures at the POSA server shows the following evolutionary relationship:



    A superposition of the structures is shown below.


    3hm4 (green), 1squ (cyan), 1xko (lightmagenta), 1xkr (yellow), 2f9z (salmon), 2hp7 (lightgrey)




    No references found.

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