Bacteriophage T7 replisome is one of the simplest replication machinery and we study the complexities of replication mechanism exploring this system. T7 gene 4 protein (gp4) assembles as a hexameric ring-shaped helicase with translocation polarity of 5' to 3' on ssDNA and duplex DNA unwinding during DNA replication. This protein also has a primase domain that generates short RNA primers for priming lagging strand DNA synthesis. It is known that T7 helicase coordinates with T7 DNA polymerase (T7gp5 -Thioredoxin of E. coli) in replisome to catalyze both leading and lagging strand DNA synthesis. However, functional and the physical extent of this relationship is not understood well. We have analyzed chemical coupling and physical proximity of these two motors during DNA replication in this study. Long standing question in the field has been that how does helicase couple the chemical energy of nucleotide hydrolysis for its translocation during DNA replication? This question could not be answered reliably so far due to the complexity and incompatibility of the NTP hydrolysis and helicase translocation activities. using pre-steady state kinetics approach combined with a novel coupling assay we have tackled this question. This is first ever report for the chemical step size determination for the helicase in replisome. Fine details of the energy coupling mechanism of the helicase in replisome are also revealed in these results. Second part of the study demonstrated the relative position of helicase and DNA polymerase in the replisome at the fork during DNA replication.