Cloning and expression of the Moraxella catarrhalis lactoferrin receptor genes.
The lactoferrin receptor genes from two strains of Moraxella catarrhalis have been cloned and sequenced. The lfr genes are arranged as lbpB followed by lbpA, a gene arrangement found in lactoferrin and transferrin receptor operons from several bacterial species. In addition, a third open reading frame, orf3, is located one nucleotide downstream of lbpA. The deduced lactoferrin binding protein A (LbpA) sequences from the two strains were found to be 99% identical, the LbpB sequences were 92% identical, and the ORF3 proteins were 98% identical. The lbpB gene was PCR amplified and sequenced from a third strain of M. catarrhalis, and the encoded protein was found to be 77% identical and 84% similar to the other LbpB proteins. Recombinant LbpA and LbpB proteins were expressed from Escherichia coli, and antisera raised to the purified proteins were used to assess antigenic conservation in a panel of M. catarrhalis strains. The recombinant proteins were tested for the ability to bind human lactoferrin following gel electrophoresis and electroblotting, and rLbpB, but not rLbpA, was found to bind lactoferrin. Bactericidal antibody activity was measured, and while the anti-rLbpA antiserum was not bactericidal, the anti-rLbpB antisera were found to be weakly bactericidal. Thus, LbpB may have potential as a vaccine candidate.
Pasteur Merieux Connaught Canada Research Centre, North York, Ontario, Canada M2R 3T4.
R P
RP
Du
Q
Q
Wang
Y P
YP
Yang
A B
AB
Schryvers
P
P
Chong
M H
MH
Klein
S M
SM
Loosmore
D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000276:immunology; D001426:Bacterial Proteins; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000276:immunology; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000378:metabolism; D015870:Gene Expression; D005798:Genes, Bacterial; D006168:Guinea Pigs; D006801:Humans; D008969:Molecular Sequence Data; D001936:Moraxella catarrhalis / Q000235:genetics* / Q000276:immunology; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; C112566:LBPA protein, Neisseria meningitidis; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; C027768:lactoferrin binding proteins, bacterial; C038340:lactoferrin receptors