CheZ is the chemotaxis signal-terminating phosphatase of Pseudomonas putida KT2440. It accelerates the dephosphorylation of the phosphorylated response regulator CheY (CheY-P), the diffusible output of the chemotaxis two-component system. By lowering CheY-P levels, CheZ resets the signaling pathway after stimulation, controlling the proportion of phosphorylated CheY that reaches the flagellar motor and thereby tuning the balance between smooth swimming and reorientation (run/reversal-tumble bias). The protein belongs to the CheZ family (Pfam PF04344; InterPro IPR007439) of response-regulator aspartyl-phosphate phosphatases, which share a conserved C-terminal catalytic region acting on the phosphorylated aspartate of CheY. CheZ acts in the cytoplasm, typically as a homodimer, and in many bacteria is enriched at chemoreceptor/chemotaxis signaling clusters through interaction with other Che proteins. In P. putida KT2440 the gene (PP_4339) lies within a flagella-mediated swimming chemotaxis operon, where CheZ supports motile foraging through complex chemical environments such as the soil and rhizosphere.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | MODIFY | Summary: CheZ is a protein-aspartate (CheY-P) phosphatase; "catalytic activity" is correct but uninformatively general. Reason: The InterPro2GO mapping assigns the root catalytic activity term, but CheZ has a well-defined, specific activity as a phosphoprotein phosphatase acting on phosphorylated CheY (an aspartyl-phosphate). UniProt itself maps the Protein phosphatase keyword for this entry to GO:0004721. Replace with the more specific molecular function term. Proposed replacements: phosphoprotein phosphatase activity |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: CheZ acts in the cytoplasm; consistent with UniProt subcellular location and the family's biology. Reason: The UniProt record annotates Cytoplasm as the subcellular location, and CheZ-family phosphatases are soluble cytoplasmic proteins (acting on diffusible CheY-P, often enriched at cytoplasmic chemotaxis clusters). The IEA mapping from the Swiss-Prot subcellular location vocabulary is appropriate. |
| GO:0009288 bacterial-type flagellum | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: CheZ is a cytoplasmic signaling phosphatase, not a structural component of the flagellum. Reason: This located_in annotation comes from an InterPro2GO mapping that conflates chemotaxis with the flagellar apparatus. CheZ is a soluble cytoplasmic enzyme that modulates the chemotaxis response regulator CheY; it is not a structural part of the bacterial-type flagellum and does not localize to the flagellar structure. The functional connection to motility is captured better by the chemotaxis process terms, and localization is already correctly represented by the cytoplasm annotation. |
| GO:0050920 regulation of chemotaxis | IEA GO_REF:0000002 | ACCEPT | Summary: CheZ regulates chemotaxis by dephosphorylating CheY-P to terminate and reset the signaling output. Reason: This is the core biological role of CheZ. By accelerating CheY-P dephosphorylation it controls the level of the chemotaxis output signal and thereby regulates chemotactic behavior. Supported by the conserved CheZ-family function and the UniProt FUNCTION annotation; the InterPro-based IEA is appropriate. |
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