Staphylococcus aureus has clustered tRNA genes

Abstract

The polymerase chain reaction (PCR) was used to detect large tRNA gene clusters in Bacillus subtilis, Bacillus badius, Bacillus megaterium, Lactobacillus brevis, Lactobacillus casei, and Staphylococcus aureus. The primers were based on conserved sequences of known gram-positive bacterial tRNA(Arg) and tRNA(Phe) genes. This PCR procedure detected an unusually large tRNA gene cluster in S. aureus. PCR-generated probes were used to identify a 4.5-kb EcoRI fragment that contained 27 tRNA genes immediately 3' to an rRNA operon. Some of these 27 tRNA genes are very similar, but only 1 is exactly repeated in the cluster. The 5' end of this cluster has a gene order similar to that found in the 9- and 21-tRNA gene clusters of B. subtilis. The 3' end of this S. aureus cluster exhibits more similarity to the 16-tRNA gene cluster of B. subtilis. The 24th, 25th, and 26th tRNA genes of this S. aureus tRNA gene cluster code for three similar, unusual Gly-tRNAs that may be used in the synthesis of the peptidoglycan in the cell wall but not in protein synthesis. Southern analysis of restriction digests of S. aureus DNA indicate that there are five to six rRNA operons in this bacterium's genome and that most or all may have large tRNA gene clusters at the 3' end.

Synthesis of Mosaic Peptidoglycan Cross-bridges by Hybrid Peptidoglycan Assembly Pathways in Gram-positive Bacteria

“…This implies that E. faecalis produces glycyl-tRNAs, which were efficiently used by the Fem transferases. Fractionation of the tRNAs isoacceptor of glycine and sequence analysis have raised the possibility that staphylococci produce unusual tRNAs dedicated to peptidoglycan synthesis (30,31). Our analysis indicates that these putative tRNAs are unlikely to play a key role in the specificity of the Fem transferases for the amino acids incorporated into the side chains of peptidoglycan precursors.…”

tRNA genes of Streptomyces lividans: new sequences and comparison of structure and organization with those of other bacteria

“…Furthermore, the highly conserved A at position 37 is replaced with a C and a sixth base pair can be formed in the anticodon stem, shortening the anticodon loop to just 5 nt. The same structure was also found in a tRNAGlY(GGA) from Staphylococcus epidermidis (25) involved in nonribosomal peptidoglycan biosynthesis and in three genes for highly similar tRNAs found in the 27-tRNA-gene cluster of Staphylococcus aureus (6). This would allow an additional base pair in the anticodon loop to be formed, perhaps impeding correct codon-anticodon interaction.…”

“…In the gram-positive bacterium B. subtilis, the 69 known tRNA genes are in only nine transcription units with up to 21 genes (without any duplicates) in a single cluster (4). An even larger cluster, containing 27 tRNA genes, occurs in Staphylococcus aureus (6). In E. coli, 78 tRNA genes are in 40 transcription units, with never more than seven genes in a cluster (13).…”

Anchor Structure of Staphylococcal Surface Proteins

“…FemA and FemB are thought to each add two additional glycines, thereby synthesizing cross-bridges with three and five glycyl, respectively (29). It is conceivable that each Fem factor might recognize one of the three glycyl tRNA species (35,36). If so, one would predict that mutations in any one of the three glycyl tRNA genes should cause the same phenotype as the corresponding fem mutants.…”

“…Three glycyl tRNA species are dedicated to this biosynthetic pathway (33)(34)(35)(36). After being charged with amino acid, these tRNAs are thought to serve as substrate in a sequence of reactions that successively add glycine either directly to the ⑀-amino of lysyl or to the amino of another glycyl (31,34).…”