TlpC, a novel chemotaxis protein in Rhodobacter sphaeroides, localizes to a discrete region in the cytoplasm.

Journal article

TlpC is encoded in the second chemotaxis operon of Rhodobacter sphaeroides. This protein shows some homology to membrane-spanning chemoreceptors of many bacterial species but, unlike these, is essential for R. sphaeroides chemotaxis to all compounds tested. Genomic replacement of tlpC with a C-terminal gfp fusion demonstrated that TlpC localized to a discrete cluster within the cytoplasm. Immunogold electron microscopy also showed that TlpC localized to a cytoplasmic electron-dense region. Correct TlpC-GFP localization depended on the downstream signalling proteins, CheW3, CheW4 and CheA2, and was tightly linked to cell division. Newly divided cells contained a single cluster but, as the cell cycle progressed, a second cluster appeared close to the initial cluster. As elongation continued, these clusters moved apart so that, on septation, each daughter cell contained a single TlpC cluster. The data presented suggest that TlpC is either a cytoplasmic chemoreceptor responding to or integrating global signals of metabolic state or a novel and essential component of the chemotaxis signalling pathway. These data also suggest that clustering is essential for signalling and that a mechanism may exist for targeting and localizing proteins within the bacterial cytoplasm.

Authors: Wadhams, G; Martin, A; Porter, S; Maddock, JR; Mantotta, J

• Publication status: Published
• Journal: Molecular microbiology
• Volume: 46
• Issue: 5
• Pages: 1211-1221
• Publication date: 2002-12-01
• DOI: 10.1046/j.1365-2958.2002.03252.x
• EISSN: 1365-2958
• ISSN: 0950-382X
• Language: English
• Keywords: Bacterial Proteins; Rhodobacter sphaeroides; Immunohistochemistry; Luminescent Proteins; Green Fluorescent Proteins; Chemotaxis; Cytoplasm; Gene Deletion; Recombinant Fusion Proteins; Membrane Proteins