Iron-regulated outer membrane protein of Bacteroides fragilis involved in heme uptake.

Under iron starvation, Bacteroides fragilis expresses various iron-regulated outer membrane proteins. In this study, a deferrated minimal medium was used in growth experiments, and the role of one of these iron-regulated outer membrane proteins (a 44-kDa protein) in an iron uptake mechanism which acquires iron from heme compounds was elucidated. When a specific 44-kDa protein antiserum was used in a medium with heme as the only iron source, growth inhibition was observed. These results demonstrate that the 44-kDa outer membrane protein plays an important role in the uptake of heme in B. fragilis.