Poster abstracts

Poster number 17 submitted by Daisy Hamburg

Identification of methylation sites on Thermus thermophilus ribosomal protein L11

Daisy-Malloy Hamburg (Department of Chemistry, University of Cincinnati), Anne McLachlan, Patrick A. Limbach (Department of Chemistry, University of Cincinnati), Hasan Demirci, Steven T. Gregory, Albert E. Dahlberg (Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University)

Abstract:
In this work, we use mass spectrometry to identify the methylation sites on T. thermophilus ribosomal protein L11. Protein L11, located in the 50S subunit of the ribosome, is known to be post-translationally trimethylated at several residues by a single methyltransferase, PrmA. L11, the most heavily methylated component of the bacterial translational apparatus, is universally conserved and actively participates in interactions of the ribosome with protein synthesis factors during initiation, elongation and termination phases of translation. L11 in Escherichia coli is known to be trimethylated at three positions: the á-amino group of the N-terminal amino acid and the å-amino group of lysine 3 and lysine 39 [2]. MALDI-TOF MS data of L11 in T. thermophilus revealed that L11 is trimethylated at an additional fourth residue [2]. Recently, Demirci et al [3] described four structures of PrmA from T. thermophilus, revealing how PrmA can position the L11 substrate for multiple consecutive side-chain methylation reactions. Here we use LC MS/MS to deduce the location of the fourth trimethylation.

References:
[1] Dognin MJ, Wittman-Liebold B (1980) Eur J Biochem 112: 131-151.
[2] Cameron DM, Gregory ST, Thompson J, Suh MJ, Limbach PA, Dahlberg AE (2004a) J Bacteriol 186: 5819-5825.
[3] Demirci H, Gregory S, Dahlberg AE, Jogi G (2007) EMBO J 26: 567-577.

Keywords: Methylation, LC MSMS