COMPLETE SEQUENCE OF OMP1, THE STRUCTURAL GENE ENCODING THE 40-KDA OUTER-MEMBRANE PROTEIN OF FUSOBACTERIUM-NUCLEATUM STRAIN FEV1

The sequence of the omp1 gene coding for the 40-kDa outer membrane pro tein (OMP) of the Gram- oral bacterium, Fusobacterium nucleatum strain Fev1, has been determined. Degenerate oligodeoxyribonucleotide primer s were used to prime the amplification of a 120-mer sequence of the ge ne. This sequence was successively used for constructing new primers a pplied in asymmetrical, symmetrical, and inverse polymerase chain reac tion using as template genomic DNA, self-ligated DNA fragments, or fra gments ligated into either pGEM-7Zf+ or pACYC184. The codon usage of t he gene was unusual in that A or T was used as the third base in the c 6don triplets in all cases, except for those amino acids (aa) which ha ve only one or two possible codon choices. Only 35 of the 61 sense cod ons were used. The aa sequence of the protein was deduced; it consiste d of 348 aa (M(r) 39 954), which is in good agreement with the 40-kDa size estimated from electrophoretic analyses. The mature protein was p receeded by a 20-aa signal peptide.