The Arg279Glu Substitution in the Adenovirus Type 11p (Ad11p) Fiber Knob Abolishes EDTA-Resistant Binding to A549 and CHO-CD46 Cells, Converting the Phenotype to That of Ad7p

Abstract

The major determinant of adenovirus (Ad) attachment to host cells is the C-terminal knob domain of the trimeric fiber protein. Ad type 11p (Ad11p; species B2) in contrast to Ad7p (species B1) utilizes at least two different cellular attachment receptors, designated sBAR (species B adenovirus receptor) and sB2AR (species B2 adenovirus receptor). CD46 has recently been identified as one of the Ad11p attachment receptors. However, CD46 did not seem to constitute a functional receptor for Ad7p. Although Ad7p shares high knob amino acid identity with Ad11p, Ad7p is deficient in binding to both sB2AR and CD46. To determine what regions of the Ad11p fiber knob are necessary for sB2AR-CD46 interaction, we constructed recombinant fiber knobs (rFK) with Ad11p/Ad7p chimeras and Ad11p sequences having a single amino acid substitution from Ad7p. Binding of the constructs to A549 and CHO-CD46 BC1 isoform-expressing cells was analyzed by flow cytometry. Our results indicate that an Arg279Glu substitution is sufficient to convert the Ad11p receptor-interaction phenotype to that of Ad7p and abolish sB2AR and CD46 interaction. Also a Glu279Arg substitution in Ad7p rFKs increases CD46 binding. Thus, the lateral HI loop of the Ad11p fiber knob seems to be the key determinant for Ad11p sB2AR-CD46 interaction. This result is comparable to another non-coxsackie-adenovirus receptor binding Ad (Ad37p), where substitution of one amino acid abolishes virus-cell interaction. In conjunction with previous results, our findings also strongly suggest that sB2AR is equivalent to CD46.

Role of Cellular Heparan Sulfate Proteoglycans in Infection of Human Adenovirus Serotype 3 and 35

“…Importantly, our previous study showed that receptor X is identical for Ad3, 7, 11p and 14 [3]. This novel receptor-usage based grouping system is supported by studies from others and us that also found CD46-usage for Ad serotype 11p, 16, 21, 35 and 50 but not for serotype 3 and 7 [4]–[7]. The finding that Ad11p is the only species B Ad family member that evolved to efficiently use both CD46 and receptor X has also been indicated by other previous studies from Gustafsson et al and Marttila et al [4],[7].…”

“…This novel receptor-usage based grouping system is supported by studies from others and us that also found CD46-usage for Ad serotype 11p, 16, 21, 35 and 50 but not for serotype 3 and 7 [4]–[7]. The finding that Ad11p is the only species B Ad family member that evolved to efficiently use both CD46 and receptor X has also been indicated by other previous studies from Gustafsson et al and Marttila et al [4],[7]. Marttila et al confirmed that CD46 blockade on human cells did not affect Ad3 and Ad7 infection, only partially inhibited Ad11p infection and completely abolished infection by serotype 16, 21, 35 and 50 [4].…”

Selection Pressure in the Human Adenovirus Fiber Knob Drives Cell Specificity in Epidemic Keratoconjunctivitis

“…To determine if the observed structural variations overlap cellular receptor binding sites, we mapped the known HAdV-cellular receptor interactions for CAR, CD46, and GD1a glycan on the homology model (16,20,32,44,(48)(49)(50)(51)(52)(53)(54). The two structural variations viewed in a surface filled model (Fig.…”

Electrostatic Interactions between Complement Regulator CD46(SCR1-2) and Adenovirus Ad11/Ad21 Fiber Protein Knob

“…Species B viruses are distinguishable from their ability to severely infect the respiratory tract, urinary tract, and kidney. Some subspecies like the B2 adenovirus 11 are primarily responsible for urinary tract infections, while others like the B1 adenovirus 21 are more associated with ocular and respiratory diseases [ 5 , 7 – 9 , 11 , 16 ]. Since no specialized treatments against these B adenoviruses are currently available, it is of particular interest to study how they interact with the immune system at the molecular level.…”

“…Each of the many capsid vertices on adenoviruses 11 and 21 has a trimeric fiber protein consisting of an N-terminus, an elongated shaft, and a globular knob domain that binds with CD46 [ 1 , 2 , 6 , 7 , 11 , 19 ]; the knob domains of Ad11 and Ad21 are called Ad11k and Ad21k, respectively, hereafter. Crystal structures show that the viral knob domain is a trimeric ligand with three identical protomers, and each protomer binds to a specific part of a CD46 molecule ( Figure 1(a) ).…”