HUMAN CYTOMEGALOVIRUS UL138 PROTEIN: PREDICTION OF PHYSICOCHEMICAL PROPERTIES, PROTEIN STRUCTURE, AND AMINO ACID PHOSPHORYLATION AND MUTATION SITES

Bioinformatics analysis of HCMV UL138 protein

Abstract

Human cytomegalovirus (HCMV) infection is usually asymptomatic in healthy individuals but the virus may be fetal in immunocompromised individuals because of reactivation of latent infection. HCMV UL138, a latency-associated determinant, encodes a 169-amino acid protein of unknown function. This study employed online bioinformatics tools to predict UL138 protein physicochemical properties, secondary and tertiary structures, and phosphorylation and mutation sites. UL138 protein was predicted to have a theoretical isoelectric point (pI) of 6.51, an instability index of 53.62, a half-life of 30 hours in mammalian eukaryotic cell, hydropathicity of -0.101 (a hydrophilic protein), 37.3% ?-helical structure, 16.6% extended ?-strands, 3.0% ?-turns and 43.1% random coils. The protein lacked a canonical N-terminal signal sequence or cleavage site, but contained an internal transmembrane domain indicating a group II integral membrane protein with 11 predicted serine phosphorylation sites all located in the ectodomain, which also contains a domain with a tertiary structure highly similar to toll-like receptor 4. Comparison of 38 known UL138 protein sequences deposited in a database with that of reference UL138 ACL51196.1 revealed the presence of 24 mutant amino acid positions, with occurrences ranging from 3 to 16%, all located in the protein ectodomain. In conclusion, the information obtained should assist in furthering knowledge of the role of UL138 protein in HCMV latency state.