Related Experiment Video
Updated: Aug 25, 2026

A Fast and Reliable Pipeline for Bacterial Transcriptome Analysis Case study: Serine-dependent Gene Regulation in Streptococcus pneumoniae
Published on: April 25, 2015
Characterization of Streptococcus pneumoniae TrmD, a tRNA methyltransferase essential for growth
Karen O'Dwyer1, Joseph M Watts, Sanjoy Biswas
1Microbial, Musculoskeletal and Proliferative Diseases CEDD, GlaxoSmithKline, Collegeville, Pennsylvania 19426, USA.
Abstract:
Down-regulation of expression of trmD, encoding the enzyme tRNA (guanosine-1)-methyltransferase, has shown that this gene is essential for growth of Streptococcus pneumoniae. The S. pneumoniae trmD gene has been isolated and expressed in Escherichia coli by using a His-tagged T7 expression vector. Recombinant protein has been purified, and its catalytic and physical properties have been characterized. The native enzyme displays a molecular mass of approximately 65,000 Da, suggesting that streptococcal TrmD is a dimer of two identical subunits. In fact, this characteristic can be extended to several other TrmD orthologs, including E. coli TrmD. Kinetic studies show that the streptococcal enzyme utilizes a sequential mechanism. Binding of tRNA by gel mobility shift assays gives a dissociation constant of 22 nM for one of its substrates, tRNA(Leu)(CAG). Other heterologous nonsubstrate tRNA species, like, tRNA (Thr)(GGT), tRNA(Phe), and tRNA (Ala)(TGC), bind the enzyme with similar affinities, suggesting that tRNA specificity is achieved via a postbinding event(s).
Related Concept Videos
Transcription Attenuation in Prokaryotes
There are several different mechanisms used to attenuate transcription. In ribosome mediated...
Stringent Response in E. coli
Bacterial RNA Polymerase
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
Bacterial RNA Polymerase
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
Coordination of Gene Expression Processes in Bacteria
Repressible Operon: trp Operon

