title: Identification of amino acids in the leader peptide of Methanococcus voltae preflagellin that are important in posttranslational processing.
abstract: Archaeal flagellins are made initially as preproteins with short, positively charged leader peptides. Analysis of all available archaeal preflagellin sequences indicates that the -1 position is always held by a glycine while the -2 and -3 positions are almost always held by charged amino acids. To evaluate the importance of these and other amino acids in the leader peptides of archaeal flagellins for processing by a peptidase, Methanococcus voltae mutant FlaB2 preflagellin genes were generated by PCR and the proteins tested in a methanogen preflagellin peptidase assay that detects the removal of the leader peptide from preflagellin. When the -1 position was changed from glycine to other amino acids tested, no cleavage was observed by the peptidase, with the exception of a change to alanine at which poor, partial processing was observed. Amino acid substitutions at the -2 lysine position resulted in a complete loss of processing by the peptidase, while changes at the -3 lysine resulted in partial processing. A mutant preflagellin with a leader peptide shortened from 12 amino acids to 6 amino acids was not processed. When the invariant glycine residue present at position +3 was changed to a valine, no processing of this mutant preflagellin was observed. The identification of critical amino acids in FlaB2 required for proper processing suggests that a specific preflagellin peptidase may cleave archaeal flagellins by recognition of a conserved sequence of amino acids.
authors.affiliation: Department of Microbiology and Immunology, Queen's University, Kingston, Ontario, Canada.
authors.forename: N A
authors.initials: NA
authors.lastname: Thomas
authors.forename: E D
authors.initials: ED
authors.lastname: Chao
authors.forename: K F
authors.initials: KF
authors.lastname: Jarrell
mesh_terms: D000595:Amino Acid Sequence; D005408:Flagellin; D017017:Methanococcus / Q000737:chemistry*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry*; D011498:Protein Precursors; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals
chemical_list: D009842:Oligopeptides; D011498:Protein Precursors; D021382:Protein Sorting Signals; C403641:preflagellin; D005408:Flagellin