Sequence of the DNA ligase-encoding gene from Thermus scotoductus and conserved motifs in DNA ligases

By dideoxynucleotide sequencing of a genomic clone, we have determined the complete nucleotide sequence of the gene encoding NAD+-dependent DNA ligase (EC 6.5.1.2) of the thermophilic bacterium Thermus scotoductus. The gene encodes a 674-amino-acid thermostable enzyme highly similar to other bacterial DNA ligases and to parts of the deduced gene product of Escherichia coli ORF f562, 5′ to the spoR gene encoding 5' guanosyl kinase.