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J. Bacteriol., Mar 1997, 1764-1773, Vol 179, No. 5
J Klesney-Tait, TJ Hiltke, I Maciver, SM Spinola, JD Radolf and EJ Hansen
The major outer membrane protein (MOMP) of Haemophilus ducreyi is an OmpA
homolog that migrates on sodium dodecyl sulfate-polyacrylamide gel
electrophoresis (SDS-PAGE) gels as three species with apparent molecular
weights ranging from 37,000 to 43,000. Monoclonal antibodies directed
against this macromolecule were used to identify recombinant clones
containing fragments of the gene encoding this protein. Nucleotide sequence
analysis of these fragments confirmed that the MOMP encoded by the intact
gene (momp) was a member of the OmpA family of outer membrane proteins.
Construction of an isogenic H. ducreyi mutant unable to express the MOMP
led to the discovery of a second outer membrane protein which migrated at
the same rate on SDS-PAGE gels as the MOMP. N-terminal amino acid sequence
analysis of this second protein revealed that its N terminus was nearly
identical to that of the MOMP and also had homology with members of the
OmpA family. Nucleotide sequence analysis of the region downstream from the
momp gene revealed the presence of a partial open reading frame encoding a
predicted OmpA-like protein. A modification of anchored PCR technology was
used to obtain the nucleotide sequence of this downstream gene which was
shown to encode a second OmpA homolog (OmpA2). The N-terminal amino acid
sequence of OmpA2 was identical to that of the OmpA-like protein detected
in the momp mutant. The H. ducreyi MOMP and OmpA2 proteins, which
comigrated on SDS-PAGE gels and which were encoded by the tandem arranged
momp and ompA2 genes, were 72% identical.
Copyright © 1997, American Society for Microbiology
The major outer membrane protein of Haemophilus ducreyi consists of two OmpA homologs
Department of Microbiology, University of Texas Southwestern Medical Center, Dallas 75235, USA.
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