Hydration and structural alterations of A-DNA. Implications for the accuracy of dna replication

The accuracy of replication, transcription and translation depends on the c orrect pairing of complementary bases of nucleic acids. However, sequence d ependent structural variations of double helices may interfere with the fid elity of these processes in altering base pair conformations. Irregular con formations; of the template-primer DNA duplex can induce replication errors in altering the structure of the polymerase active site. However, ir most DNA polymerases,water exclusion induces the duplex to adopt the A-conformat ion. In attenuating the structural variability, the A-form enhances replica tion fidelity. How hydration and DNA sequence modulate the structure of A-D NA is therefore a relevant question for better understanding the mechanisms of sequence directed mutagenesis. This Study is focused on the relationshi ps between hydration and the distortion of A-DNA double helices. The crysta llographic analysis of the hydration pattern of A-DNA decamers reveals that the subtle interplay of DNA sequence and hydration helps to stabilize unus ual structures. These findings are discussed in the context of the accuracy of replication.