Identification of amino acids in the leader peptide of Methanococcus voltae preflagellin that are important in posttranslational processing

Thomas, NA Chao, ED Jarrell, KF

Na. Thomas et al., Identification of amino acids in the leader peptide of Methanococcus voltae preflagellin that are important in posttranslational processing, ARCH MICROB, 175(4), 2001, pp. 263-269

27

INGLESE

Article

Microbiology

ARCHIVES OF MICROBIOLOGY

0302-8933 → ACNP

175

4

2001

263 - 269

ISI

0302-8933(200104)175:4<263:IOAAIT>2.0.ZU;2-B

Archaeal flagellins are made initially as preproteins with short, positivel y 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 e valuate the importance of these and other amino acids in the leader peptide s of archaeal flagellins for processing by a peptidase, Methanococcus volta e mutant FlaB2 preflagellin genes were generated by PCR and the proteins te sted in a methanogen preflagellin peptidase assay that detects the removal of the leader peptide from preflagellin. When the -1 position was changed f rom glycine to other amino acids tested, no cleavage was observed by the pe ptidase, with the exception of a change to alanine at which poor, partial p rocessing was observed. Amino acid substitutions at the -2 lysine position resulted in a complete loss of processing by the peptidase, while changes a t 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 pro cessed. When the invariant glycine residue present at position +3 was chang ed to a valine, no processing of this mutant preflagellin was observed. The identification of critical amino acids in FlaB2 required for proper proces sing suggests that a specific preflagellin peptidase may cleave archaeal fl agellins by recognition of a conserved sequence of amino acids.