From a paper just published online yesterday in Nature,
The work reveals that some conventional boundaries between the kingdoms of life are not as rigid as has been thought. For instance, the researchers suggest that one bacterial lineage synthesizes purine bases — building blocks of DNA and RNA — using enzymes previously thought to exist only in archaea. Meanwhile, three of the archaeal cells sequenced in the study harbour sigma factors, which initiate RNA transcription and have previously been found only in bacteria.
And another novel solution has been uncovered:
The researchers also found a bacterium that has ‘recoded’ the three-letter series of bases UGA — known as the opal stop codon. In almost every other organism, this nucleotide sequence signals the cell to stop translating RNA into protein. But in this organism, it tells the cell to make the amino acid glycine. The team propose to place it into a new bacterial phylum, called Gracilibacteria.
Nature doi:10.1038/nature.2013.13361