A 40-kDa lactoferrin-binding protein was identified in a strain of Pre
votella nigrescens isolated from a patient with periodontitis. The pro
tein was purified by affinity column chromatography using a Sepharose-
lactoferrin column and detergent-solubilized membranes. The N-terminal
sequence revealed no apparent similarities with any other sequenced b
acterial protein. The native conformation of the 40-kDa protein was a
condition to bind either iron-free or iron-saturated lactoferrin. A po
ssible function of this Lf-binding protein could be related with an ir
on acquisition mechanism in P. nigrescens.