Full Length Research Paper

Proteomics of Marburg and Ebola glycoproteins: Insights into their physicochemical similarities and irregularities

Misaki, Wayengera^{1, 2}*, Henry, Kajumbula², Kaddu, D. Mulindwa², Joseph Olobo² and Wilson, Byarugaba³

¹Division of Human and Molecular genetics, Faculty of Medicine, Makerere University, P.O. Box 7072 Kampala, Uganda.

²Division of Molecular Biology Department of Microbiology, Faculty of Medicine, Makerere University, P. O. Box 7072 Kampala, Uganda.

³Department of Pathology, Faculty of Medicine, Makerere University, P. O. Box 7072 Kampala, Uganda.

*Corresponding author. E-mail: wmisaki@yahoo.com.

Abbreviations: GP, Glycoprotein; VHF, viral hemorrhagic fever; EBO, Ebola; MBG, Marburg; II, instability index; Asp, aspartate; Glu, glutamine; C, carbon; N, nitrogen; H, hydrogen; O, oxygen; S, sulfur; ExPASy, Expert Protein Analysis  System.

Accepted 5 February, 2008

Ebola (EBO) and Marburg (MBG) form the two major genus of a class of negatively stranded RNA viruses responsible for viral hemorrhagic fevers (VHF) in equatorial Africa called filoviridae. Pathogenesis of VHF is thought to be mediated by the envelope glycoproteins (GP). Although both viruses have been found to be closely related, with a side by side alignment of the gene sequences of the Ebola and Marburg viruses and comparison of protein products showing similarities, there is absence of immunological cross reactivity. The physicochemical properties of the two GP may in part explain this. Using a 676 aa Ebola and 681 aa Marburg GP protein sequences; and the ExPASy Server ProtParam, the physicochemical properties of both proteins were derived and compared. The MBG-GP molecular weight was bigger and more negatively charged than EBO (MW=74481 vs.74464.4 and overall charge=-11 vs.-9). Other constants analyzed respectively: for MBG versus EBO (1) theoretical PI: 5.85 vs. 6.16, (2) extinction coefficient (82110/1.102 vs 100100/1.344 M-1 cm-1 at 280 nm/H2O). The Estimated half life for both glycoproteins was 30 h, although MBG-GP was unstable compared to EBO-GP (The instability index [II]; MBG vs EBO = 42.82 vs. 38.36). These variations must be taken into account in research and development of a common vaccine against both MBG and EBO.

Key words: Ebola, Marburg, glycoproteins, proteomics, vaccine research.