The roles of submolecular regions of OmpF and OmpC, major outer membrane proteins of Escherichia coli, as concerns their biogenesis, structure and function were studied using a large number of chimeric genes constructed from the ompF and ompC genes through single or double homologous in vivo recombination. When recombination between the two genes took place at certain regions of their central regions, no chimeric protein was detected, irrespective of whether the amino-terminal and carboxy-terminal regions were derived from OmpF or OmpC. Biochemical studies revealed that these proteins were synthesized and exported across the cytoplasmic membrane normally, but that they were not properly assembled into the outer membrane and hence were degraded rapidly. Characterization of these chimeric proteins, in which recombination between OmpF and OmpC took place once or twice, suggested that the central region of each of these proteins plays an important role in the respective assembly, whereas the roles of the amino-terminal and carboxy-terminal regions may be marginal. Functional characterization of these chimeric proteins revealed the regions important for the receptor functions of OmpF and OmpC for phages TuIa and TuIb, respectively.

Amino Acid Sequence↗

PubMedDate not supplied

Combined medical and surgical treatment of severe vernal keratoconjunctivitis.

PURPOSE: We report the efficacy of an alternative method of treatment for vernal keratoconjunctivitis (VKC) that consists of excision of the palpebral conjunctiva followed by supratarsal injection of corticosteroid and five times daily topical application of 0.05% cyclosporine A (CsA) and cromolyn sodium. METHODS: We evaluated 10 patients with severe treat-resistant VKC with corneal complications. The patients were evaluated for symptoms and for signs, including conjunctival changes, corneal limbal infiltrates, vascularization, reduction of epitheliopathy, meibomitis, visual acuity, intraocular pressure, and pathologic evaluation, before and after treatment. RESULTS: All patients showed marked improvement after 2 weeks of treatment. The symptoms (P <.01), signs (P <.02), and the visual acuity of all patients (P <.01) had significantly improved following treatment. Histological examination showed significant inflammatory cell decreases 4 weeks after surgery (P <. 05). CONCLUSION: Surgery plus topical drug therapy may be useful in treating patients with very severe VKC.

Adolescent↗