Comparative analysis of the Hom family of outer membrane proteins in isolates from two geographically distinct regions: The United States and South Korea

Background Helicobacter pylori encodes numerous outer membrane proteins ( OMP s), but only a few have been characterized in depth. Deletion, duplication, and allelic variation of many of the H. pylori OMP s have been reported, which suggests that these proteins may play key roles in host adaptation. Herein, we characterize the variation observed within the Hom family of OMP s in H. pylori obtained from two geographically distinct populations. Materials and Methods PCR genotyping of the hom genes was carried out using clinical isolates from South Korea and the United States. A combination of statistical, phylogenetic, and protein modeling analyses was conducted to further characterize the hom variants. Results Variations in the closely related hom genes, homA and homB , occur in regions that are predicted to encode environmentally exposed loops. A similar phenomenon is true for homC S as compared to homC L . Conversely, little variation was observed in homD . Certain variants of the Hom family of proteins were more prominent in isolates from the Korean population as compared to isolates from the United States. Conclusion En masse , our data show that the homA , homB , and homC profiles vary based upon the geographic origin of the strain; however, the fourth member of the hom family, homD , is more highly conserved. Additionally, protein topology modeling showed that many of the less well‐conserved regions between homA and homB and between homC S and homC L corresponded to predicted environmentally exposed loops, suggesting that the divergence of the Hom family may be due to host adaptation/pressure.