biostudies-literatureWard CKNIAID NIH HHS6013-22https://www.ebi.ac.uk/biostudies/studies/S-EPMC107678biostudies-literatureUnknown180(22)We have identified two extremely large open reading frames (ORFs) in Haemophilus ducreyi 35000, lspA1 and lspA2, each of which encodes a predicted protein product whose N-terminal half is approximately 43% similar to the N-terminal half of Bordetella pertussis filamentous hemagglutinin (FhaB). To the best of our knowledge, lspA1 (12,500 nucleotides [nt]) and lspA2 (14,800 nt) are among the largest prokaryotic ORFs identified to date. The predicted proteins, LspA1 and LspA2, are 86% identical overall to each other and also have limited amino acid sequence similarity at their N termini to other secreted bacterial proteins, including certain hemolysins. Southern blot analysis indicated that lspA1 and lspA2 sequences were present in 15 other geographically diverse H. ducreyi strains. Reverse tJournal of bacteriologyHaemophilus ducreyi secretes a filamentous hemagglutinin-like protein.PMC107678F32-AI09845AI32011Cope LDHansen EJWard CKLumbley SRLatimer JLfalseHaemophilus ducreyi secretes a filamentous hemagglutinin-like protein.We have identified two extremely large open reading frames (ORFs) in Haemophilus ducreyi 35000, lspA1 and lspA2, each of which encodes a predicted protein product whose N-terminal half is approximately 43% similar to the N-terminal half of Bordetella pertussis filamentous hemagglutinin (FhaB). To the best of our knowledge, lspA1 (12,500 nucleotides [nt]) and lspA2 (14,800 nt) are among the largest prokaryotic ORFs identified to date. The predicted proteins, LspA1 and LspA2, are 86% identical overall to each other and also have limited amino acid sequence similarity at their N termini to other secreted bacterial proteins, including certain hemolysins. Southern blot analysis indicated that lspA1 and lspA2 sequences were present in 15 other geographically diverse H. ducreyi strains. Reverse t1998-01-01T00:00:00Z1998 Nov2025-04-04T09:53:14.251Z2019-03-27T00:16:58ZS-EPMC107678981166210.1128/JB.180.22.6013-6022.1998