An edge-gated injection molding apparatus is disclosed for distributing a melt stream to a plurality of mold cavities aligned on opposing sides of an injection manifold assembly. The injection manifold assembly includes melt outlets aligned on opposing sides thereof with a nozzle seal in fluid communication with each melt outlet for transferring the melt stream to a corresponding mold cavity. A sliding relationship between each nozzle seal and its respective melt outlet while the nozzle seal is securely held relative to the mold gate permits misalignment between the nozzle seal and its respective melt outlet in the cold condition without causing stress on the nozzle seal. Under operating conditions, the sliding relationship permits subsequent alignment between the nozzle seal and its respective melt outlet. The nozzle seal has a two-piece gate seal with components thereof threadably coupled to each other such that relative rotation therebetween applies a sealing preload.