Colman PM

Ferreira L

Green ED

Hermentin P

Iorio RM

Mahon PJ

Merz DC

Miura N

Portner A

Potier M

Spiro RG

Suzuki T

Wang ZM

Yewdell J

ABSTRACT
          
            The human parainfluenza virus (hPIV) hemagglutinin-neuraminidase (HN) protein binds (H) oligosaccharide receptors that contain
            N
            -acetylneuraminic acid (Neu5Ac) and cleaves (N) Neu5Ac from these oligosaccharides. In order to determine if one of HN′s two functions is predominant, we measured the affinity of H for its ligands by a solid-phase binding assay with two glycoprotein substrates and by surface plasmon resonance with three monovalent glycans. We compared the dissociation constant (
            
              K
              d
            
            ) values from these experiments with previously determined Michaelis-Menten constants (
            
              K
              m
            
            s) for the enzyme activity. We found that glycoprotein substrates and monovalent glycans containing Neu5Acα2-3Galβ1-4GlcNAc bind HN with
            
              K
              d
            
            values in the 10 to 100 μM range.
            
              K
              m
            
            values for HN were previously determined to be on the order of 1 mM (M. M. Tappert, D. F. Smith, and G. M. Air, J. Virol. 85:12146–12159, 2011). A
            
              K
              m
            
            value greater than the
            
              K
              d
            
            value indicates that cleavage occurs faster than the dissociation of binding and will dominate under N-permissive conditions. We propose, therefore, that HN is a neuraminidase that can hold its substrate long enough to act as a binding protein. The N activity can therefore regulate binding by reducing virus-receptor interactions when the concentration of receptor is high.
          </jats:p

Mary M. Tappert

J. Zachary Porterfield

Padmaja Mehta-D'Souza

Shelly Gulati

Gillian M. Air

Crossref

Journal of Virology

Quantitative Comparison of Human Parainfluenza Virus Hemagglutinin-Neuraminidase Receptor Binding and Receptor Cleavage

Quantitative Comparison of Human Parainfluenza Virus Hemagglutinin-Neuraminidase Receptor Binding and Receptor Cleavage

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