Journal Article

Mutagenesis of tyrosine and di-leucine motifs in the HIV-1 envelope cytoplasmic domain results in a loss of Env-mediated fusion and infectivity

Hunter, Eric, Prince, Jessica L, Claiborne, Daniel T, Bhakta, Sushma J, Shang, Liang

2011

Overview

Background The gp41 component of the Human Immunodeficiency Virus (HIV) envelope glycoprotein (Env) contains a long cytoplasmic domain (CD) with multiple highly conserved tyrosine (Y) and dileucine (LL) motifs. Studies suggest that the motifs distal to major endocytosis motif (Y 712 HRL), located at residues 712-715 of Env, may contribute to Env functionality in the viral life cycle. In order to examine the biological contribution of these motifs in the biosynthesis, transport, and function of Env, we constructed two panels of mutants in which the conserved Y- and LL-motifs were sequentially substituted by alternative residues, either in the presence or absence of Y 712 . Additional mutants targeting individual motifs were then constructed. Results All mutant Envs, when expressed in the absence of other viral proteins, maintained at least WT levels of Env surface staining by multiple antibodies. The Y 712 mutation (Y712C) contributed to at least a 4-fold increase in surface expression for all mutants containing this change. Sequential mutagenesis of the Y- and LL-motifs resulted in a generally progressive decrease in Env fusogenicity. However, additive mutation of dileucine and tyrosine motifs beyond the tyrosine at residue 768 resulted in the most dramatic effects on Env incorporation into virions, viral infectivity, and virus fusion with target cells. Conclusions From the studies reported here, we show that mutations of the Y- and LL-motifs, which effectively eliminate the amphipathic nature of the lytic peptide 2 (LLP2) domain or disrupt YW and LL motifs in a region spanning residues 795-803 (YWWNLLQYW), just C-terminal of LLP2, can dramatically interfere with biological functions of HIV-1 Env and abrogate virus replication. Because these mutant proteins are expressed at the cell surface, we conclude that tyrosine and di-leucine residues within the cytoplasmic domain of gp41 play critical roles in HIV-1 replication that are distinct from that of targeting the plasma membrane.

• Publisher: BioMed Central,BioMed Central Ltd,BMC
• Subject: Amino Acid Motifs / Amino Acid Sequence / Amino Acid Substitution - genetics / Animals / Antibodies / Biomedical and Life Sciences / Biomedicine / Cancer Research / Cell Line / Cercopithecus aethiops / DNA Mutational Analysis / env Gene Products, Human Immunodeficiency Virus - genetics / env Gene Products, Human Immunodeficiency Virus - metabolism / Gene mutations / Genetic aspects / HIV infection / HIV-1 - genetics / HIV-1 - physiology / Humans / Infectious Diseases / Leucine / Leucine - genetics / Molecular Sequence Data / Mutagenesis, Site-Directed / Mutation, Missense / Physiological aspects / Protein Structure / Risk factors / Tyrosine / Tyrosine - genetics / Vaccine / Viral Fusion Proteins - genetics / Viral Fusion Proteins - metabolism / Virology / Virulence Factors - genetics / Virulence Factors - metabolism / Virus Internalization