T. Caldas et al., Translational defects of Escherichia coli mutants deficient in the Um(2552) 23S ribosomal RNA methyltransferase RrmJ/FTSJ, BIOC BIOP R, 271(3), 2000, pp. 714-718
Citations number
28
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
We recently identified RrmJ (alias FtsJ), the first encoded protein of the
rrmJ-hflB heat shock operon, as an Um(2552) methyltransferase of the 23S rR
NA. We now report that the rrmJ-deficient strain exhibits growth and transl
ational defects compared to the wild-type strain. Growth rates of the rrmJ
mutant are decreased at both low and high temperatures. Protein synthesis a
ctivity is reduced up to 65% when S-30 rrmJ mutant extracts are tested in a
coupled in vitro transcription/translation assay. In vitro methylation of
these extracts by RrmJ partially restores protein synthesis activity. Polys
ome profile analysis of the rrmJ strain reveals an increase in the proporti
on of free 30S and 50S subunits at both 30 and 42 degrees C. These results
suggest that the RrmJ-catalyzed methylation of Um(2552) in 23S RNA strength
ens ribosomal subunit interactions, increases protein synthesis activity, a
nd improves cell growth rates even at non-heat shock. temperatures. (C) 200
0 Academic Press.