Human milk lactoferrin is a serine protease that cleaves <i>Haemophilus</i> surface proteins at arginine‐rich sites

Hendrixson, David R.; Qiu, Jiazhou; Shewry, Steven C.; Fink, Doran L.; Petty, Stephen E.; Baker, Edward N.; Plaut, Andrew G.; Geme, Joseph W. St.

doi:10.1046/j.1365-2958.2003.03327.x

Cited by 100 publications

(65 citation statements)

References 48 publications

(58 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…1A). The required protease activity could have been provided by either lactoferrin (25,38) or pneumococci (11). Pretreatment of apo-hLf with PMSF, SBTI, or PMSF plus SBTI (followed by inactivation of the excess protease inhibitor by overnight incubation in an aqueous solution) failed to prevent killing of bacteria by apohLf (Fig.…”

Section: Resultsmentioning

confidence: 98%

“…Human apolactoferrin has an inefficient yet highly specific protease activity (25,38), but there is no evidence that it catalyzes autocleavage of apo-hLf or that one apo-hLf molecule can cleave another apo-hLf molecule. If LLP were released from apo-hLf by host proteases in serum and secretions, the highly charged peptides might be lost by associating with host molecules before they encounter bacteria.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Serine Protease PrtA from Streptococcus pneumoniae Plays a Role in the Killing of S. pneumoniae by Apolactoferrin

et al. 2011

View full text Add to dashboard Cite

It is known that apolactoferrin, the iron-free form of human lactoferrin, can kill many species of bacteria, including Streptococcus pneumoniae. Lactoferricin, an N-terminal peptide of apolactoferrin, and fragments of it are even more bactericidal than apolactoferrin. In this study we found that apolactoferrin must be cleaved by a serine protease in order for it to kill pneumococci. The serine protease inhibitors were able to block killing by apolactoferrin but did not block killing by a lactoferrin-derived peptide. Thus, the killing of pneumococci by apolactoferrin appears to require a protease to release a lactoferricin-like peptide(s). Incubation of apolactoferrin with growing pneumococci resulted in a 12-kDa reduction in its molecular mass, of which about 7 to 8 kDa of the reduction was protease dependent. Capsular type 2 and 19F strains with mutations in the gene encoding the major cell wall-associated serine protease, prtA, lost much of their ability to degrade apolactoferrin and were relatively resistant to killing by apolactoferrin (P < 0.001). Recombinant PrtA was also able to cleave apolactoferrin, reducing its mass by about 8 kDa, and greatly enhance the killing activity of the solution containing the apolactoferrin and its cleavage products. Mass spectroscopy revealed that PrtA makes a major cut between amino acids 78 and 79 of human lactoferrin, removing the N-terminal end of the molecule (about 8.6 kDa). The simplest interpretation of these data is that the mechanism by which apolactoferrin kills Streptococcus pneumoniae requires the release of a lactoferricin-like peptide(s) and that it is this peptide(s), and not the intact apolactoferrin, which kills pneumococci.Streptococcus pneumoniae is a major inhabitant of the human upper respiratory tract and can cause pneumonia, sepsis, meningitis, and otitis media (21a). Pneumococci are common inhabitants of the nasopharynx of healthy children and adults. Pneumococci can cause serious disease when they leave the nasopharynx and successfully invade the middle ear, lungs, blood, or brain (21a). Although specific antibody can mediate protection against pneumococcal infection (14, 53), there is also evidence that antibody is not necessary for immunity to colonization and that innate immunity plays a significant role (30,50,58). Moreover, the molecular mechanisms involved in the interaction of S. pneumoniae with the innate immune system are incompletely understood.Known innate immune system components that protect against bacterial infection in the upper airways include mucus flow, antibacterial proteins, such as lysozyme and lactoferrin, and antibacterial peptides, such as ␣-defensins and ␤-defensins (57). Human lactoferrin (hLf) has been reported to play a number of different roles in mammals, including immunoregulation, iron sequestration, promotion of calcium uptake, and bactericidal activity (52). The observation that pneumococcal surface protein A (PspA) specifically inhibits in vitro killing of pneumococci by apolactoferrin (apo-hLf), the iron-free for...

show abstract

Section: Resultsmentioning

confidence: 98%

mentioning

confidence: 99%

Serine Protease PrtA from Streptococcus pneumoniae Plays a Role in the Killing of S. pneumoniae by Apolactoferrin

et al. 2011

View full text Add to dashboard Cite

show abstract

“…Besides being cleaved by pepsin and other proteases, HLf itself may act as a protease. The proteolytic activity of HLf that has been described previously takes place at serine residues surrounded by arginines (RSRR or RRSR) (21). However, these sites are not found in the three major Ad2 or Ad5 capsid proteins (hexon, fiber, and penton base).…”

Section: Discussionmentioning

confidence: 93%

Adenoviruses Use Lactoferrin as a Bridge for CAR-Independent Binding to and Infection of Epithelial Cells

Johansson¹,

Jönsson²,

Marttila³

et al. 2007

J Virol

View full text Add to dashboard Cite

Most adenoviruses bind to the coxsackie-and adenovirus receptor (CAR). Surprisingly, CAR is not expressed apically on polarized cells and is thus not easily available to viruses. Consequently, alternative mechanisms for entry of coxsackievirus and adenovirus into cells have been suggested. We have found that tear fluid promotes adenovirus infection, and we have identified human lactoferrin (HLf) as the tear fluid component responsible for this effect. HLf alone was found to promote binding of adenovirus to epithelial cells in a dose-dependent manner and also infection of epithelial cells by adenovirus. HLf was also found to promote gene delivery from an adenovirus-based vector. The mechanism takes place at the binding stage and functions independently of CAR. Thus, we have identified a novel binding mechanism whereby adenovirus hijacks HLf, a component of the innate immune system, and uses it as a bridge for attachment to host cells.

show abstract

“…This effect does not seem to be related to the binding of Fe, which is needed by most bacteria; rather, it is the result of a destabilizing effect on the outer cell membrane of bacteria, making them more sensitive to lysozyme, which is also present in the milk (Ellison, 1994;Leitch & Willcox, 1998). Lactoferrin promotes growth of the strictly anaerobic Bifidobacteria, but it also cleaves colonization factors on the potential pathogen Haemophilus influenzae and hinders the mucosal adherence of enteropathogenic E. coli (Hendrixson et al 2003;Ochoa et al 2003). Furthermore, it has antiviral effects and acts against fungi such as Candida albicans (Nikawa et al 1994).…”

Section: Lactoferrinmentioning

confidence: 99%

Session 1: Feeding and infant development Breast-feeding and immune function

2007

View full text Add to dashboard Cite

The newborn receives, via the placenta, maternal IgG antibodies against the microbes present in its surroundings, but such antibodies have a pro-inflammatory action, initiating the complement system and phagocytes. Although the host defence mechanisms of the neonate that involve inflammatory reactivity are somewhat inefficient, this defence system can still have catabolic effects. Breast-feeding compensates for this relative inefficiency of host defence in the neonate by providing considerable amounts of secretory IgA antibodies directed particularly against the microbial flora of the mother and her environment. These antibodies bind the microbes that are appearing on the infant's mucosal membranes, preventing activation of the pro-inflammatory defence. The major milk protein lactoferrin can destroy microbes and reduce inflammatory responses. The non-absorbed milk oligosaccharides block attachment of microbes to the infant's mucosae, preventing infections. The milk may contain anti-secretory factor, which is anti-inflammatory, preventing mastitis in mothers and diarrhoea in infants. Numerous additional factors in the milk are of unknown function, although IL-7 is linked to the larger size of the thymus and the enhanced development of intestinal Tgd lymphocytes in breast-fed compared with non-breast-fed infants. Several additional components in the milk may help to explain why breast-feeding can reduce infant mortality, protecting against neonatal septicaemia and meningitis. It is therefore important to start breast-feeding immediately. Protection is also apparent against diarrhoea, respiratory infections and otitis media. There may be protection against urinary tract infections and necrotizing enterocolitis, and possibly also against allergy and certain other immunological diseases, and tumours. In conclusion, breast-feeding provides a very broad multifactorial anti-inflammatory defence for the infant.

show abstract

Human milk lactoferrin is a serine protease that cleaves Haemophilus surface proteins at arginine‐rich sites

Cited by 100 publications

References 48 publications

Serine Protease PrtA from Streptococcus pneumoniae Plays a Role in the Killing of S. pneumoniae by Apolactoferrin

Serine Protease PrtA from Streptococcus pneumoniae Plays a Role in the Killing of S. pneumoniae by Apolactoferrin

Adenoviruses Use Lactoferrin as a Bridge for CAR-Independent Binding to and Infection of Epithelial Cells

Session 1: Feeding and infant development Breast-feeding and immune function

Contact Info

Product

Resources

About