Polar assembly of the type IV pilus secretin in Myxococcus xanthus.
The type IV pilus filament of Myxococcus xanthus penetrates the outer membrane through a gated channel--the PilQ secretin. Assembly of the channel and formation of PilQ multimeric complexes that resist disassembly in heated detergent is correlated with the release of a 50 kDa fragment of PilQ. Tgl lipoprotein is required for PilQ assembly in M. xanthus, because PilQ monomers but no heat and detergent-resistant complexes are present in a strain from which tgl has been deleted. PilQ protein is often found in single patches at both poles of the cell. Tgl, however, is found in a patch at only one pole that most likely identifies the piliated cell pole. Tgl protein that has been transferred from another cell by contact stimulation leads to secretin assembly in the recipient. Pilus proteins PilQ, PilG, PilM, PilN, PilO and PilP are also required for the donation of Tgl by contact stimulation to a stimulation recipient. We suggest that these proteins are parts of a polar superstructure that holds PilQ monomers in a cluster and ready for Tgl to bring about secretin assembly.
Department of Developmental Biology, Stanford University School of Medicine, B300 Beckman Center, 279 Campus Drive, Stanford, CA 94305, USA.
Eric
E
Nudleman
Daniel
D
Wall
Dale
D
Kaiser
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D016764:Cell Polarity; D036781:Fimbriae Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D016941:Myxococcus xanthus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D018933:Pili, Sex; D012633:Secretin / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
D001426:Bacterial Proteins; D008565:Membrane Proteins; C107109:Tgl protein, Myxococcus xanthus; C084295:pilQ protein, bacteria; D012633:Secretin; D036781:Fimbriae Proteins