Topological analysis and role of the transmembrane domain in polar targeting of PilS, a Pseudomonas aeruginosa sensor kinase.
In Pseudomonas aeruginosa, synthesis of pilin, the major protein subunit of the pili, is regulated by a two-component signal transduction system in which PilS is the sensor kinase. PilS is an inner membrane protein found at the poles of the bacterial cell. It is composed of three domains: an N-terminal hydrophobic domain; a central cytoplasmic linker region; and the C-terminal transmitter region conserved among other sensor kinases. The signal that activates PilS and, consequently, pilin transcription remains unknown. The membrane topology of the hydrophobic domain was determined using the lacZ and phoA gene fusion approach. In this report, we describe a topological model for PilS in which the hydrophobic domain forms six transmembrane helices, whereas the N- and C-termini are cytoplasmic. This topology is very stable, and the cytoplasmic C-terminus cannot cross the inner membrane. We also show that two of the six transmembrane segments are sufficient for membrane anchoring and polar localization of PilS.
Ethier
J
J
University of Calgary, Microbiology and Infectious Diseases, 3330 Hospital Drive, NW, Calgary, Alberta, Canada, T2N 4N1.
Boyd
J M
JM
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D036781:Fimbriae Proteins; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D018933:Pili, Sex / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
D001426:Bacterial Proteins; D008565:Membrane Proteins; D014157:Transcription Factors; C080687:pilS protein, Bacteria; D036781:Fimbriae Proteins; D011494:Protein Kinases