Molecular analysis of an outer membrane protein, MopB, of Methylococcus capsulatus (Bath) and structural comparisons with proteins of the OmpA family.
The gene encoding a major outer membrane protein (MopB) of the methanotroph Methylococcus capsulatus (Bath) was cloned and sequenced. The cloned DNA contained an open reading frame of 1044 bp coding for a 348-amino-acid polypeptide with a 21-amino-acid leader peptide. Comparative sequence analysis of the predicted amino acid sequence revealed that the C-terminal part of MopB possessed sequences that are conserved in the OmpA family of proteins. The N-terminal half of the protein had no significant sequence similarity to other proteins in the databases, but the predicted secondary structure showed stretches of amphipathic beta-strands typical of transmembrane segments of outer membrane proteins. A region with four cysteines similar to the cysteine-encompassing region of the OprF of Pseudomonas aeruginosa was found toward the C-terminal part of MopB. Results from whole-cell labeling with the fluorescent thiol-reacting reagent 5-iodoacetamidofluorescein indicated a surface-exposed location for these cysteines. A probe consisting of the 3'-end of the mopB gene hybridized to the type I methanotroph Methylomonas methanica S in Southern blots containing DNA from nine methanotrophic strains representing six different genera.
Fjellbirkeland
A
A
Department of Molecular Biology, University of Bergen, Norway. Anne.Fjellbirkeland@mbi.uib.no
Bemanian
V
V
McDonald
I R
IR
Murrell
J C
JC
Jensen
H B
HB
D020561:Alphaproteobacteria / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D015139:Blotting, Southern; D003001:Cloning, Molecular; D020563:Gammaproteobacteria / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D008697:Methane / Q000378:metabolism; D020619:Methylococcus capsulatus / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D001425:Bacterial Outer Membrane Proteins; C417085:MopB protein, Methylococcus; C078167:OMPA outer membrane proteins; D008697:Methane