Highly conserved residues in the helical domain of dengue virus type 1 precursor membrane protein are involved in assembly, prM protein cleavage and entry.
Hsieh SC, Wu YC, Zou G, Nerurkar VR, Shi PY, Wang WK.
Hsieh SC, Wu YC, Zou G, Nerurkar VR, Shi PY, Wang WK. (2014) Highly conserved residues in the helical domain of dengue virus type 1 precursor membrane protein are involved in assembly, prM protein cleavage and entry. Journal of Biological Chemistry 289(48):33149-33160.
The envelope and precursor membrane (prM) proteins of dengue virus (DENV) are present on the surface of immature virions. During maturation, prM protein is cleaved by furin protease into pr peptide and membrane (M) protein. While previous studies mainly focusing on the pr region have identified several residues important for DENV replication, the functional role of M protein, particularly the Ã????Ã???Ã??Ã?Â±-helical domain (MH) which is predicted to undergo a large conformational change during maturation, remains largely unknown. In this study, we investigated the role of nine highly conserved MH domain residues in the replication cycle of DENV by site-directed mutagenesis in a DENV1 prME expression construct and found that alanine substitutions introduced to four highly conserved residues at the C-terminus and one at the N-terminus of the MH domain greatly affect the production of both virus-like particles and replicon particles. Eight out of the nine alanine mutants affected the entry of replicon particles, which correlated with the impairment in prM cleavage. Moreover, seven mutants were found to have reduced prM-E interaction at low pH, which may inhibit the formation of smooth immature particles and exposure of prM cleavage site during maturation, thus contributing to inefficient prM cleavage. Taken together, this is the first report showing that highly conserved MH domain residues, located at 20 to 38 amino acids downstream from the prM cleavage site, can modulate the prM cleavage, maturation of particles and virus entry. The highly conserved nature of these residues suggests potential targets of antiviral strategy.