title: Bacteroid-encoded proteins are secreted into the peribacteroid space by Rhizobium leguminosarum.
abstract: Bacteroids of Rhizobium leguminosarum in root nodules of Pisum sativum are enclosed by a plant-derived peribacteriod membrane (PBM). The contents of the interstitial peribacteroid space (PBS) between bacteroid membrane and PBM were isolated by a controlled osmotic shock of PBM-enclosed bacteroids and analysed by two-dimensional gel electrophoresis. Silver staining revealed approximately 40 PBS polypeptides. Ex planta (35)S-methionine labeling of PBM-enclosed bacteroids revealed that about 90% of the PBS proteins are synthesized by the bacteroid. Approximately 30% of the PBS polypeptides are common between the PBS and the periplasmic space of free-living bacteria; one (38kDa) PBS protein is also excreted by free-living bacteria in the bacterial culture medium. At least four bacteroid-encoded PBS polypeptides were clearly identified as symbiosis-specific.
authors.affiliation: Department of Molecular Biology, Agricultural University, De Dreijen 11, 6703 BC, Wageningen, Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Katinakis
authors.forename: R M
authors.initials: RM
authors.lastname: Lankhorst
authors.forename: J
authors.initials: J
authors.lastname: Louwerse
authors.forename: A
authors.initials: A
authors.lastname: van Kammen
authors.forename: R C
authors.initials: RC
authors.lastname: van den Bos