Functional analysis of amino acids at stalk/head interface of human parainfluenza virus type 3 hemagglutinin-neuraminidase protein in the membrane fusion process

Abstract

Human parainfluenza virus type 3 (hPIV3) is an important respiratory pathogen that causes the majority of viral pneumonia of infants and young children. hPIV3 can infect host cells through the synergistic action of hemagglutinin-neuraminidase (HN) protein and the homotypic fusion (F) protein on the viral surface. HN protein plays a variety of roles during the virus invasion process, such as promoting viral particles to bind to receptors, cleaving sialic acid, and activating the F protein. Crystal structure research shows that HN tetramer adopted a "heads-down" conformation, at least two heads dimmer on flank of the four-helix bundle stalk, which forms a symmetrical interaction interface. The stalk region determines interactions and activation of F protein in specificity, and the heads in down position statically shield these residues. In order to make further research on the function of these amino acids at the hPIV3 HN stalk/head interface, fifteen mutations (8 sites from stalk and 7 sites from head) were engineered into this interface by site-directed mutagenesis in this study. Alanine substitution in this region of hPIV3 HN had various effects on cell fusion promotion, receptor binding, and neuraminidase activity. Besides, L151A also affected surface protein expression efficiency. Moreover, I112A, D120A, and R122A mutations of the stalk region that were masked by global head in down position had influence on the interaction between F and HN proteins.

Phylogenetic analysis of human parainfluenza type 3 virus strains responsible for the outbreak during the COVID-19 pandemic in Seoul, South Korea

“…HN protein is a homotetrameric type II integral membrane protein consisting of a cytoplasmic domain, transmembrane domain, helical stalk, and globular head (37). Three functions of the HN protein have been identified so far: 1) hemagglutinin activity for receptor binding, 2) neuraminidase activity for receptor cleavage by hydrolyzing sialic acid residues, and 3) fusion activation that interacts with the F protein (38). HN and F proteins work in tandem to infect the host cells.…”

Phylogenetic analysis of human parainfluenza type 3 virus strains responsible for the outbreak during the COVID-19 pandemic in Seoul, South Korea

“…The A22T and K31N mutations do not belong to the stalk, globular, or F-specific regions. Although we could not determine whether these mutations can significantly affect the infectivity of HPIV3 or alter the structure of proteins, further research is needed, as certain mutations have been reported to have a significant effect on viral activity (38).…”

Kinetic analysis of paramyxovirus-sialoglycan receptor interactions reveals virion motility

“…It has a short N-terminal cytoplasmic tail, transmembrane domain, stalk region and C-terminal six-bladed β-propeller head domain typical of sialidases, which contains the catalytic site. The HN catalytic site functions both in sialoglycan receptor binding and cleavage [17][18][19]. The stalk domain of HN physically interacts with the F protein and plays a role in triggering the F protein rearrangements leading to membrane fusion [15].…”