Ribosomal RNA mutations to rifampicin resistance
Date
2012-01-17
Authors
Macheke, Rulane Glenda
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Abstract
In prokaryotes, transcription and translation are coupled and as a result, the beginning of the
messenger RNA is translated by the ribosome while the 3' end is still synthesized. How
exactly this occurs is still not clear. One possibility is that RNA polymerase and the
ribosomes may be in physical contact with each other at some stage during gene expression
or RNA polymerase has a binding site in the ribosomes. Mutational analysis is one method to
explore how coordination between these two moieties occurs in bacteria.
An Escherichia coli strain with all seven chromosomal ribosomal RNA operons deleted,
replaced by a single rrnB plasmid-borne operon, was used to isolate ribosomal RNA mutants
with increased rifampicin resistance, two of which were studied further. The altered rrnB
operon in pGM1 was obtained by spontaneous whilst in pGM2 by EMS mutagenesis. The
mutated rrnB operon in pGM1 conferred resistance to 25μg/ml of rifampicin while in pGM2
resistance of 30μg/ml was observed. A base substitution of T to A at position 355 of the 23S
rRNA was detected in pGM1and no nucleotide change was detected in pGM2. The successful
isolation of ribosomal RNA mutants with rifampicin resistance is consistent with the
hypothesis of interaction between the RNA polymerase and the ribosomes and suggests the
part of this interaction is with the large ribosomal subunit.
Description
MSc., Faculty of Science, University of the Witwatersrand, 2011
Keywords
RNA, Ribosomes