The nucleotide sequence of Bacillus subtilis tRNA genes

Area of Science:

• Molecular Biology
• Genetics
• Microbiology

Background:

• Transfer RNA (tRNA) genes are essential for protein synthesis.
• Bacterial tRNA gene organization can vary and is crucial for gene expression.

Purpose of the Study:

• To isolate and characterize Bacillus subtilis tRNA genes.
• To determine the sequence and organization of a cluster of tRNA genes.
• To identify regulatory elements associated with these tRNA genes.

Main Methods:

• Isolation of recombinant phage clones containing tRNA genes using a lambda 816 library.
• Hybridization with unfractionated tRNA probes.
• Southern blot analysis to locate tRNA genes on a DNA fragment.
• DNA sequencing to determine gene organization and identify promoter regions.

Main Results:

• A 3-kb fragment from recombinant phage lambda 816-BS83 contained a cluster of four tRNA genes: tDNALys, tDNAGlu, tDNAAsp, and tDNAPhe.
• The gene order was determined as tDNALys-9bp-tDNAGlu-81bp-tDNAAsp-30bp-tDNAPhe.
• Sequence analysis confirmed expected RNA sequences for tDNALys and tDNAPhe.
• Two genes (tDNALys, tDNAAsp) encoded the 3'-terminal CCA sequence, while tDNAGlu and tDNAPhe did not.
• A promoter-like sequence, potentially a sigma 55-recognition site, was found upstream of tDNALys.

Conclusions:

• A novel cluster of four tRNA genes in Bacillus subtilis has been identified and characterized.
• The gene organization and presence of a promoter-like sequence suggest coordinated regulation of these tRNA genes.
• The differential encoding of the 3'-terminal CCA sequence may have implications for tRNA processing and function.