Itive search for orthologues of the 147 S. coelicolor TTA-containing genes (or in some cases gene clusters). We identified 19 that were widespread and frequently TTA-containing in 13 other Streptomyces genomes (Table 2). In addition, a further 10 genes or gene clusters frequently had TTA codons, even though their S. coelicolor orthologues were TTA-free (asterisks in Table 2). As 27/29 of the TTA-c