Complete sequence of omp1, the structural gene encoding the 40-kDa outer membrane protein of Fusobacterium nucleatum strain Fev1

Abstract

The sequence of the omp1 gene coding for the 40-kDa outer membrane protein (OMP) of the Gram − oral bacterium, Fusobacterium nucleatum strain Fev1, has been determined. Degenerate oligodeoxyribonucleotide primers were used to prime the amplification of a 120-mer sequence of the gene. This sequence was successively used for constructing new primers applied in asymmetrical, symmetrical, and inverse polymerase chain reaction using as template genomic DNA, self-ligated DNA fragments, or fragments ligated into either pGEM-7Zf + or pACYC184. The codon usage of the gene was unusual in that A or T was used as the third base in the codon triplets in all cases, except for those amino acids (aa) which have only one or two possible codon choices. Only 35 of the 61 sense codons were used. The aa sequence of the protein was deduced; it consisted 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 preceeded by a 20-aa signal peptide.