Augmented synthesis of periplasmic alkaline phosphatase from E. coli DH1 coded by the phoA gene within the composition of plasmid pHI-7 results in alterations in the enzyme biogenesis, such as accumulation of intermediate enzyme forms corresponding to various stages of its posttranslational modification, and alternative localization. The cell cytoplasm was found to contain a large proportion of alkaline phosphatase precursors in the form of insoluble aggregates. The mature enzyme was detected in both the periplasm and the cultural fluid in the form three methazymes with an increased (as compared with the original strain) content of methazymes I and II. The cell envelope of E. coli DHI transformed by plasmid pHI-7 with the phoA gene differed from that of the original strain by an increased acid phospholipid (cardiolipin/phosphatidylglycerol) ratio as well as by increased distribution density of intramembrane particles on the surface of the cytoplasmic membrane facing the cytoplasm. Changes in the biogenesis of the enzyme during its augmented synthesis are due to disturbances in the equilibrium between the synthesis of polypeptide chains, on the one hand, and their translocation and processing, on the other, apparently as a result of restricted secretion sites and lack of inhibition of translation of secreted proteins in bacteria.