Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/7167
In former investigations (unpublished) a new type I polymerase (Family A), different to the prevalent one of Thermus, was found in a Thermus antranikianii. It has conserved domain structures, related to the distinct polymerase I subgroup of Aquificales and seems to feature strand displacement activity (unpublished) similar to the polymerase from phage phi29. The distribution of the gene in the Thermus genus was investigated with a PCR-screening. The gene was found to be present in some but not all strains of the species T. thermophilis (21% of strains examined), T. scotoductus (15% of strain examined), T. igniterrae (28% of strains examined) and T. brockianus (35% of strains examined), but not in T. oshimai. Prior sequence analysis of the gene flanking regions already had revealed that the gene is located in close proximity to a transposase gene, thus linked to it in Thermus antranikianii. The same linkage was observed in other Thermus strains, where the polymerase was present, by PCR-screening. The aquificae like PolI polymerase has sporadic distribution in other bacterial phyla. Only in the Aquificae phylum itself, where it is found in every species/strain examined. This is a very unusual species-distribution indicating later gene transfer. The distribution pattern in Thermus is even a stronger support for this hypothesis. The linkage to the transposase and other sequence features indicates also that the polymerase is transported by the means of a transposon that can move between strains and across species.
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