title: Model for membrane organization and protein sorting in the cyanobacterium Synechocystis sp. PCC 6803 inferred from proteomics and multivariate sequence analyses.
abstract: Cyanobacteria are unique eubacteria with an organized subcellular compartmentalization of highly differentiated internal thylakoid membranes (TM), in addition to the outer and plasma membranes (PM). This leads to a complicated system for transport and sorting of proteins into the different membranes and compartments. By shotgun and gel-based proteomics of plasma and thylakoid membranes from the cyanobacterium Synechocystis sp. PCC 6803, a large number of membrane proteins were identified. Proteins localized uniquely in each membrane were used as a platform describing a model for cellular membrane organization and protein intermembrane sorting and were analyzed by multivariate sequence analyses to trace potential differences in sequence properties important for insertion and sorting to the correct membrane. Sequence traits in the C-terminal region, but not in the N-terminal nor in any individual transmembrane segments, were discriminatory between the TM and PM classes. The results are consistent with a contact zone between plasma and thylakoid membranes, which may contain short-lived "hemifusion" protein traffic connection assemblies. Insertion of both integral and peripheral membrane proteins is suggested to occur through common translocons in these subdomains, followed by a potential translation arrest and structure-based sorting into the correct membrane compartment.
authors.affiliation: Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, 10691 Stockholm, Sweden.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Pisareva
authors.forename: Joseph
authors.initials: J
authors.lastname: Kwon
authors.forename: Jihyun
authors.initials: J
authors.lastname: Oh
authors.forename: Soohyun
authors.initials: S
authors.lastname: Kim
authors.forename: Changrong
authors.initials: C
authors.lastname: Ge
authors.forename: Ake
authors.initials: A
authors.lastname: Wieslander
authors.forename: Jong-Soon
authors.initials: JS
authors.lastname: Choi
authors.forename: Birgitta
authors.initials: B
authors.lastname: Norling
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D015999:Multivariate Analysis; D021381:Protein Transport; D040901:Proteomics; D046939:Synechocystis / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins