The mechanism by which genetic information is duplicated and transmitted to future generations in all organisms requires the coordination of several multi-protein complexes. These genome maintenance complexes generally bind and unwind duplex DNA to allow access to genomic information. In Escherichia coli and related bacteria, initiation of DNA replication occurs at a unique site (oriC) on a circular chromosome at which two replisome complexes assemble and then replicate bi-directionally away from this initiation site. However, approximately once per cell cycle, the replisomes encounter DNA damage or stalled protein complexes that prematurely force the replication machinery off the template, leaving partially duplicated chromosomes. This situation presents a potentially lethal situation for the cell and requires a sequence-independent system that reloads the replisome onto sites far removed from oriC. This DNA structure-dependent process of reloading the replisome is achieved through a group of proteins collectively known as the DNA replication restart primosome (RRP) and their functions are essential in bacteria. The RRP is composed of four proteins (PriA, PriB, PriC, and DnaT) that work in diverse pathways to reload the replicative helicase, DnaB, onto abandoned replication forks. PriA, a 3' to 5' helicase, is the most evolutionarily conserved member of the RRP, and it defines the dominant pathway by which replication restart occurs in bacteria. However, the lack of high-resolution structural data for PriA has hindered studies to understand how it recognizes and processes abandoned DNA replication forks. This thesis presents the first high-resolution structures of full length PriA. Models emerge explaining how PriA recognizes and remodels DNA via its intrinsic helicase activity and protein interactions that may or may not be coated with single stranded DNA binding protein (SSB). The results help to explain the results of over 30 years of biochemical experiments as well as providing novel mechanistic details of DNA replication restart.