passages.id: split_1_test_149_passage
passages.type: progene_text
passages.text: Secondary structure analysis predicts that beta43 exists as an 18 - stranded beta barrel and that Ag43 shows structural organization closely resembling that of immunoglobulin A1 protease type of exoprotein produced by pathogenic Neisseria and Haemophilus spp. The correct processing of the polyprotein to alpha43 and beta43 in OmpT , OmpP , and DegP protease - deficient E. coli strains points to an autocatalytic cleavage mechanism , a hypothesis supported by the occurrence of an aspartyl protease active site within alpha43 .