tRNA Gene Structures in Bacteria

During bacteria, tRNA molecules are designed as precursors with a lot more nucleotides both upstream and downstream in the tRNA coding sequence. To produce an adult tRNA, the endoribonuclease RNase P removes the upstream sequence, while a variety of enzymes can take off the downstream sequence. In this thesis, the influence of these upstream and downstream sequences for the expression of mature functional tRNA was studied. That it was discovered that in Escherichia coli, the existence of an upstream sequence positively influences tRNA expression. Furthermore, it was basically shown that this identity to the nucleotide immediatedly 5′ of the canonical RNase P cleavage site in the tRNA precursor influenced RNase P cleavage site selection in vivo in E. coli, yet not in Pseudomonas aeruginosa. Additionally, a stem-loop during the precursor just downstream to the tRNA increased this “miscleavage”. This stem-loop resembled a rho-independent transcription terminator and overlapped the trpT gene in P. aeruginosa, even so it only marginally impacted the expression of this downstream secE gene. The trpT and secE genes put together to become cotranscribed. The trpT-secE gene order seemed to be conserved in the greater part of bacteria investigated.The expression of tRNA genes during increase in Streptomyces coelicolor seemed to be studied. Here, the expression of many tRNA genes tested increased over time during development. ..

Contents: tRNA Gene Structures in Bacteria

Introduction
DNA, RNA, and Proteins
Transcription
Transcription generates different Classes of RNA Molecules
The Main Function of tRNA, rRNA, and mRNA is in the Production
of Proteins
tRNA Structure
tRNA Gene Structure and Organisation
tRNA Gene Structures
tRNA Gene Organisation
tRNA Gene Expression
Processing of tRNA Primary Transcripts
tRNA Modification
Degradation of tRNA molecules
Charging the tRNA with an Amino Acid
Other Functions of tRNA Molecules
tRNAs and Gene Regulation
Nonsense Suppressor tRNAs as Tools to Study tRNA Gene Expression
The Present Investigation
Aims
The Bacteria Used in this Study
Results and Discussion
The Importance of Having a 5’-leader (Paper I)
Escherichia coli and Pseudomonas aeruginosa respond differently to Changes in tRNA Gene Structure (Papers II–IV)
tRNA Expression and UUA Codon Suppression during Development
of Streptomyces coelicolor (Paper V)
Overall Conclusions
Swedish Summary
Acknowledgements
References