title: Two independent pathways for self-recognition in Proteus mirabilis are linked by type VI-dependent export.
abstract: Swarming colonies of the bacterium Proteus mirabilis are capable of self-recognition and territorial behavior. Swarms of independent P. mirabilis isolates can recognize each other as foreign and establish a visible boundary where they meet; in contrast, genetically identical swarms merge. The ids genes, which encode self-identity proteins, are necessary but not sufficient for this territorial behavior. Here we have identified two new gene clusters: one (idr) encodes rhs-related products, and another (tss) encodes a putative type VI secretion (T6S) apparatus. The Ids and Idr proteins function independently of each other in extracellular transport and in territorial behaviors; however, these self-recognition systems are linked via this type VI secretion system. The T6S system is required for export of select Ids and Idr proteins. Our results provide a mechanistic and physiological basis for the fundamental behaviors of self-recognition and territoriality in a bacterial model system.
  
  
  OBJECTIVE
  Our results support a model in which self-recognition in P. mirabilis is achieved by the combined action of two independent pathways linked by a shared machinery for export of encoded self-recognition elements. These proteins together form a mechanistic network for self-recognition that can serve as a foundation for examining the prevalent biological phenomena of territorial behaviors and self-recognition in a simple, bacterial model system.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA.
authors.forename: Larissa M
authors.initials: LM
authors.lastname: Wenren
authors.forename: Nora L
authors.initials: NL
authors.lastname: Sullivan
authors.forename: Lia
authors.initials: L
authors.lastname: Cardarelli
authors.forename: Alecia N
authors.initials: AN
authors.lastname: Septer
authors.forename: Karine A
authors.initials: KA
authors.lastname: Gibbs
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D008124:Locomotion; D008969:Molecular Sequence Data; D005810:Multigene Family; D011513:Proteus mirabilis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D004269:DNA, Bacterial