title: A multi-protein complex from Myxococcus xanthus required for bacterial gliding motility.
abstract: Myxococcus xanthus moves by gliding motility powered by Type IV pili (S-motility) and a second motility system, A-motility, whose mechanism remains elusive despite the identification of approximately 40 A-motility genes. In this study, we used biochemistry and cell biology analyses to identify multi-protein complexes associated with A-motility. Previously, we showed that the N-terminal domain of FrzCD, the receptor for the frizzy chemosensory pathway, interacts with two A-motility proteins, AglZ and AgmU. Here we characterized AgmU, a protein that localized to both the periplasm and cytoplasm. On firm surfaces, AgmU-mCherry colocalized with AglZ as distributed clusters that remained fixed with respect to the substratum as cells moved forward. Cluster formation was favoured by hard surfaces where A-motility is favoured. In contrast, AgmU-mCherry clusters were not observed on soft agar surfaces or when cells were in large groups, conditions that favour S-motility. Using glutathione-S-transferase affinity chromatography, AgmU was found to interact either directly or indirectly with multiple A-motility proteins including AglZ, AglT, AgmK, AgmX, AglW and CglB. These proteins, important for the correct localization of AgmU and AglZ, appear to be organized as a motility complex, spanning the cytoplasm, inner membrane and the periplasm. Identification of this complex may be important for uncovering the mechanism of A-motility.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3204, USA.
authors.forename: Beiyan
authors.initials: B
authors.lastname: Nan
authors.forename: Emilia M F
authors.initials: EM
authors.lastname: Mauriello
authors.forename: Im-Hong
authors.initials: IH
authors.lastname: Sun
authors.forename: Anita
authors.initials: A
authors.lastname: Wong
authors.forename: David R
authors.initials: DR
authors.lastname: Zusman
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis / Q000502:physiology*; D003593:Cytoplasm / Q000737:chemistry; D008124:Locomotion; D008954:Models, Biological; D008956:Models, Chemical; D016941:Myxococcus xanthus / Q000737:chemistry / Q000502:physiology*; D019897:Periplasm / Q000737:chemistry; D011485:Protein Binding; D025941:Protein Interaction Mapping
chemical_list: D001426:Bacterial Proteins