Yu R H, Schryvers A B
Department of Microbiology and Infectious Diseases, University of Calgary, Alberta, Canada.
Microb Pathog. 1993 May;14(5):343-53. doi: 10.1006/mpat.1993.1034.
As a first step in localizing the regions of human lactoferrin involved in binding to bacterial lactoferrin receptors, N-lobe and C-lobe fragments were assessed for binding to receptors on Neisseria meningitidis, Neisseria gonorrhoeae and Moraxella (Branhamella) catarrhalis. Preparations of N-lobe and C-lobe were obtained by tryptic digestion of iron-loaded human lactoferrin followed by separation of the two lobes by gel exclusion chromatography in 10% acetic acid. Solid phase binding studies demonstrated that the isolated C- and N-lobe preparations were capable of binding to membranes from iron-deficient N. meningitidis, N. gonorrhoeae and M. catarrhalis. The binding of the individual C- and N-lobes was confirmed by an analytical SDS-PAGE binding method in which the membrane-associated polypeptides were identified by prior biotinylation and subsequent binding of labelled streptavidin. This contrasts with bacterial transferrin receptors, which only bind to C-lobe fragment of human transferrin, indicating that the bacterial lactoferrin and transferrin receptors differ in their interaction with their respective glycoprotein ligands and may differ in the mechanism of iron removal.
作为确定人乳铁蛋白中与细菌乳铁蛋白受体结合区域的第一步，对N端叶和C端叶片段与脑膜炎奈瑟菌、淋病奈瑟菌和卡他莫拉菌（布兰汉菌属）受体的结合情况进行了评估。通过对负载铁的人乳铁蛋白进行胰蛋白酶消化，然后在10%乙酸中通过凝胶排阻色谱法分离两个叶，获得N端叶和C端叶的制剂。固相结合研究表明，分离出的C端叶和N端叶制剂能够与缺铁的脑膜炎奈瑟菌、淋病奈瑟菌和卡他莫拉菌的膜结合。通过分析SDS-PAGE结合方法证实了单个C端叶和N端叶的结合，在该方法中，通过预先生物素化和随后标记链霉亲和素的结合来鉴定膜相关多肽。这与细菌转铁蛋白受体形成对比，细菌转铁蛋白受体仅与人转铁蛋白的C端叶片段结合，表明细菌乳铁蛋白受体和转铁蛋白受体在与各自糖蛋白配体的相互作用上存在差异，并且在铁去除机制上可能也有所不同。
