title: Different minimal signal peptide lengths recognized by the archaeal prepilin-like peptidases FlaK and PibD.
abstract: In Archaea, the preflagellin peptidase (a type IV prepilin-like peptidase designated FlaK in Methanococcus voltae and Methanococcus maripaludis) is the enzyme that cleaves the N-terminal signal peptide from preflagellins. In methanogens and several other archaeal species, the typical flagellin signal peptide length is 11 to 12 amino acids, while in other archaea preflagellins possess extremely short signal peptides. A systematic approach to address the signal peptide length requirement for preflagellin processing is presented in this study. M. voltae preflagellin FlaB2 proteins with signal peptides 3 to 12 amino acids in length were generated and used as a substrate in an in vitro assay utilizing M. voltae membranes as an enzyme source. Processing by FlaK was observed in FlaB2 proteins containing signal peptides shortened to 5 amino acids; signal peptides 4 or 3 amino acids in length were unprocessed. In the case of Sulfolobus solfataricus, where the preflagellin peptidase PibD has broader substrate specificity, some predicted substrates have predicted signal peptides as short as 3 amino acids. Interestingly, the shorter signal peptides of the various mutant FlaB2 proteins not processed by FlaK were processed by PibD, suggesting that some archaeal preflagellin peptidases are likely adapted toward cleaving shorter signal peptides. The functional complementation of signal peptidase activity by FlaK and PibD in an M. maripaludis DeltaflaK mutant indicated that processing of preflagellins was detected by complementation with either FlaK or PibD, yet only FlaK-complemented cells were flagellated. This suggested that a block in an assembly step subsequent to signal peptide removal occurred in the PibD complementation.
authors.affiliation: Department of Microbiology and Immunology, Queen's University, Kingston, Ontario, Canada.
authors.forename: Sandy Y M
authors.initials: SY
authors.lastname: Ng
authors.forename: David J
authors.initials: DJ
authors.lastname: VanDyke
authors.forename: Bonnie
authors.initials: B
authors.lastname: Chaban
authors.forename: John
authors.initials: J
authors.lastname: Wu
authors.forename: Yoshika
authors.initials: Y
authors.lastname: Nosaka
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Aizawa
authors.forename: Ken F
authors.initials: KF
authors.lastname: Jarrell
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D019848:Gene Expression Regulation, Archaeal / Q000502:physiology*; D017017:Methanococcus / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D021382:Protein Sorting Signals
chemical_list: D019843:Archaeal Proteins; D021382:Protein Sorting Signals; D010447:Peptide Hydrolases