Hemin levels in culture medium of Porphyromonas (Bacteroides) gingivalis regulate both hemin binding and trypsinlike protease production

Abstract

Washed cells and Sarkosyl-insoluble outer membrane preparations of the black-pigmented bacteroides Porphyromonas gingivalis W50 bound hemin. The amount of hemin removed from a buffered solution by both cells and outer membranes was significantly larger if bacteria had been grown in broths supplemented with 5 mg of hemin per liter rather than none. Conversely, cells grown without supplemental hemin bound relatively little. However, all preparations bound some hemin. In addition, hemin regulated the production of significantly higher levels of trypsinlike protease by P. gingivalis W50. The nonpigmented variant, W50 BE1, showed no such responses to the levels of hemin in the growth medium.

Utilization of haem compounds by Aeromonas salmonicida

“…Comparison of haem-binding by iron-replete and iron-restricted cells indicated no differences in the quantity of haem bound, suggesting that the additional IROMPs expressed by iron-restricted cells are not involved in haem-binding and that binding of haem compounds and utilization by both iron-replete and iron-restricted bacteria is by a constitutive factor. This is in contrast to the iron-rcgulated haem-binding OMPs of Shigella flexneri and Escherichia coli involved in the uptake and binding of haem (Stugard et al 1989) and a number of putative haem-binding proteins induced under conditions of haem or iron-restriction (Deneer & Potter 1989;Carman, Ramakrishnan & Harper 1990;Otto, Sparrius, Verweij-van Vught & MacLaren 1990;Lcc 1992). In addition, SDS-PAGE of OMP preparations of iron-replete and ironrestricted cells confirms the work of Kay et al (1985) in that the 49-kDa A-layer surface array protein is not an iron-regulated protein.…”

Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia: the ‘red complex’, a prototype polybacterial pathogenic consortium in periodontitis

“…The maximum binding and affinity for hemin was greatest in hemin excess grown cultures, although hemin-limited P. gingivalis expressed novel outer membrane proteins that bind hemin during hemin limitation (49,51,396). Moreover, P. gingivalis W50 grown in hemin excess bound more hemin with a higher affinity than its mutant BEI under the same conditions (64,397). Smalley et al (397) showed that reduced hemin binds to P. gingivalis more than oxidized hemin.…”

Iron and heme utilization inPorphyromonas gingivalis

“…On the other hand, higher hemin level resulted in elevated cell-associated iron, which increased the capability of the pathogen to survive at times of iron deprivation. It has been speculated that under heminexcessive conditions putative hemin-inducible components might be operative in P. gingivalis and utilized for both hemin binding and transportation of this molecule from the surface of the cell membrane to the cytosolic fraction [43,157,234]. P. gingivalis growth under conditions of heme excess has been reported to enhance the virulence of the bacterium in a murine model of infection [235].…”