title: Proteomic and computational analysis of secreted proteins with type I signal peptides from the Antarctic archaeon Methanococcoides burtonii.
abstract: LC-MS/MS was used to identify secreted proteins in the Antarctic archaeon Methanococcoides burtonii. Seven proteins possessing a classical class 1 signal peptide were identified in the supernatant from cultures grown at 4 and 23 degrees C. The proteins included a putative S-layer cell surface protein, cell surface protein involved with cell adhesion, and trypsin-like serine protease. Protease activity was detected in the secreted fraction, and the signal peptide cleavage site of the protease was confirmed using Edman sequencing. The expression profile of putative cell surface proteins suggests a requirement for cell interactions during growth at low temperature. Sequences of the secreted proteins were used to compile a dataset containing a further 32 predicted secreted proteins from the Methanosarcinaceae. Many of these proteins were also S-layer cell surface proteins with a variety of predicted roles, particularly in cell-cell interaction. Computational analysis of signal peptides revealed a preference for lysine in the n-region, leucine in the h-region, and a eucaryal-type cleavage site, highlighting the mosaic nature of signal peptides in Archaea. This is the first study to experimentally characterize secreted proteins from a cold-adapted archaeon and provides new insight and a functional dataset for studying secretion in Archaea.
authors.affiliation: School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Neil F W
authors.initials: NF
authors.lastname: Saunders
authors.forename: Charmaine
authors.initials: C
authors.lastname: Ng
authors.forename: Mark
authors.initials: M
authors.lastname: Raftery
authors.forename: Michael
authors.initials: M
authors.lastname: Guilhaus
authors.forename: Amber
authors.initials: A
authors.lastname: Goodchild
authors.forename: Ricardo
authors.initials: R
authors.lastname: Cavicchioli
mesh_terms: D000595:Amino Acid Sequence; D000864:Antarctic Regions; D019843:Archaeal Proteins / Q000032:analysis* / Q000235:genetics; D002853:Chromatography, Liquid; D019295:Computational Biology / Q000379:methods*; D013058:Mass Spectrometry; D017019:Methanosarcinaceae / Q000737:chemistry*; D008969:Molecular Sequence Data; D009943:Organophosphorus Compounds; D021382:Protein Sorting Signals / Q000235:genetics*; D040901:Proteomics / Q000379:methods*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
chemical_list: C043517:2-(4-isothiocyanatophenoxy)-1,3,2-dioxaphosphinene 2-oxide; D019843:Archaeal Proteins; D009943:Organophosphorus Compounds; D021382:Protein Sorting Signals