The 40-kDa outer membrane protein has been cloned from the periodontal pathogen Porphyromonas gingivalis 381 as a 2.0-kbp EcoRI DNA fragment. This protein was found to have several functions, including aggregation and hemagglutination. On a functional motif search, we found that this molecule carried a hemin-binding domain, and the recombinant protein expressed hemin-binding activity. We deposited the DNA sequence into the NCBI DNA database as the 35-kDa hemin-binding protein (HBP35). However, promoter and terminator of the hbp35 gene have not been fully analyzed. In this study, we analyzed the nucleotide sequence of the EcoRI fragment to identify promoter and terminator regions and determined the structure of hbp35. A possible promoter sequence (TTGCAG in the -35 region and TATTTT in the -10 region), which were nearly identical to the predicted promoter sequences, were found upstream of the start codon (ATG). The number of bases between the regions was 17. The transcription start site (+1) was predicted to be located 53 nt upstream from the translation start codon. Palindrome analysis showed a very high matching sequence position from 1554 to 1601 on the EcoRI fragment. Hairpin loop and stem parts analysis predicted two typical terminators downstream of hbp35. Both locations partially overlapped the palindromic sequences, indicating ρ-independent transcription termination in the 3'-noncoding region. These terminator and promoter analyses therefore identified the whole gene structure of hbp35.