The highly conserved domain of the Caulobacter McpA chemoreceptor is required for its polar localization.
We have fused GFP to the C-terminus of McpA to study chemoreceptor polar localization in Caulobacter crescentus. The full-length McpA-GFP fusion is polarly localized and methylated. The methylation is dependent on the chemoreceptor methyltransferase (cheR) and chemoreceptor methylesterase (cheB) genes present in the mcpA operon. C-terminal and internal deletions of McpA were constructed and fused to the N-terminus of GFP to identify the domains required for polar localization. When the R1 methylation domain was deleted, the McpA-GFP fusion was still polarly localized, suggesting that this domain is dispensable for polar localization. However, when the highly conserved domain (HCD), which is involved in interacting with CheW, was deleted either by an internal deletion or C-terminal deletion, the resulting McpA-GFP fusions were completely delocalized. When the mcpA operon, which contains the cheW and cheA homologues, was deleted, the full-length McpA-GFP fusion was delocalized. Although additional chemotaxis genes are required for the polar localization of McpA-GFP, the presence of the single polar flagellum is not required. However, in filamentous cells, which are frequently found in C. crescentus fliF mutants, the McpA-GFP fusion was observed at mid-cell positions.
Alley
M R
MR
Department of Biochemistry, Imperial College of Science, Technology and Medicine, London SW7 2AY, UK. d.alley@ic.ac.uk
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism; D016935:Caulobacter crescentus / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity; D002633:Chemotaxis / Q000235:genetics; D017124:Conserved Sequence; D003593:Cytoplasm / Q000378:metabolism; D005407:Flagella / Q000502:physiology; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion
D001426:Bacterial Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D008780:Methyltransferases; C038706:chemotaxis methyltransferase; D002265:Carboxylic Ester Hydrolases; C041144:chemotactic protein methylesterase