Molecular cloning of the major outer membrane protein of Chlamydia trachomatis

Abstract

A gene library of Chiamydia trachomatis (serovar LI) DNA has been prepared in the phage vector X1059.From this bank, 20 recombinant phage-expressing components which reacted with serum from a patient with a C. trachomatis (Ll) infection were chosen. Selective expression and radiolabeling of phage polypeptides in irradiated Escherichia coli demonstrated that one of these clones encoded a polypeptide doublet with an apparent molecular weight similar to that of the C. trachomatis (Ll) major outer membrane protein. Both species of this cloned doublet (40 and 41 kilodaltons) could be immunoprecipitated by serum from a patient with a C. trachomatis (LI) infection but not by normal human serum. Components of this apparent molecular weight were not precipitated from irradiated E. coli infected with vector phage X1059 by either of these sera. Comparison of the Staphylococcus aureus-V8 protease peptide maps of these two cloned polypeptides and chlamydial major outer membrane protein extracted from elementary bodies showed all three polypeptides to produce peptide fragments of 15.5, 13.8, and 11.5 kilodaltons. Due to the indentical apparent molecular weights of the fragments produced from the 40and 41-kilodalton cloned polypeptides, these were concluded to be different conformational forms of the same molecular species. These cloned components were indistinguishable from C. trachomatis (LI) ma,jor outer membrane protein.

Primary structure of the porin protein of Haemophilus influenzae type b determined by nucleotide sequence analysis

“…For example, the leucine codon UUG was used frequently in the P1 gene but not at all in the 40 P2 gene. Similarly, the phenylalanine codon UUC was used 3 in the P2 gene much more frequently than was UUU; in the 91 P1 gene, the latter phenylalanine codon was predominant. While P2 had relatively more threonine residues than did P1, 0 the threonine codon ACG was not used at all in the P2 gene, 3 but it was used in the P1 gene.…”

“…Similarly, the phenylalanine codon UUC was used 3 in the P2 gene much more frequently than was UUU; in the 91 P1 gene, the latter phenylalanine codon was predominant. While P2 had relatively more threonine residues than did P1, 0 the threonine codon ACG was not used at all in the P2 gene, 3 but it was used in the P1 gene. Codon usage was much more similar between the Hib P1 and P2 genes, however, than it 0 was between the P2 gene and the E. coli OmpF gene.…”

“…Although extensive research has been done on the porin proteins of E. coli (34), relatively little is known about the porins of other bacterial pathogens. Genes encoding the porin proteins of other bacterial species, including Chlamydia trachomatis (3,41), Neisseria gonorrhoeae (6,11), Pseudomonas aeruginosa (46), and Salmonella typhi (2), have been cloned and expressed in E. coli, thus providing the opportunity for detailed molecular biological investigation of the structure and function of the products of these aopF IWRNlLAVIVPALLVAGTANAAEIYNKDGNKVDLYGK--AVGLHYfSKGNGENSYGGNXMTY--ARLGFKGETOINSDLTGYGOWEY ---NFOGNNSE-GAAQTGNKT-RLAFAGL--K--YADVGSFDYGRNYGV particular genes. Similarly, information about the P2 porin protein of Hib has only recently begun to accumulate (14,15,18,26,27,33,(42)(43)(44)(45), and the fact that this protein can be a target for antibodies protective against experimental Hib disease (33) underscores the importance of elucidating its immunogenic, antigenic, and functional properties.…”

“…LysGLyGLuAsnLysArgProAsnAspLysAlaGlyGLuVaLArgI leGlyGluIleAsnAsnGLyI leGLnVaLGLyALaLysTyrAspALaAsnAspI leVa LA LaLys I LeA l aTyr 3. DNA sequence of the P2 gene of Hib DL42.…”