Two early genes of bacteriophage T5 encode proteins containing an NTP-binding sequence motif and probably involved in DNA replication, recombination and repair.

It is demonstrated, by computer-assisted analysis, that T5 bacteriophage early genes D10 and D13 encode proteins containing the purine NTP-binding sequence motif. The D10 gene product is shown to be a member of a recently characterized superfamily of (putative) DNA and RNA helicases. The D13 gene product is related at a statistically significant level, to the gene 46 product of bacteriophage T4 which is a component of an exonuclease involved in phage DNA replication, recombination and repair. A lower but also significant degree of sequence similarity was detected between the gene D12 product of T5 and the gene 47 product of T4, the second component of the same nuclease. It is hypothesized that both D10 and D13 gene products of T5 might be NTPases, possibly DNA-dependent, mediating NTP-consuming steps during phage DNA replication, recombination and/or repair.