IN SILICO STRUCTURE PREDICTION OF GLOSSINA MORSITANS MORSITANS ODORANT BINDING PROTEINS

Abstract

Glossina morsitans morsitans is the primary vector for trypanosome parasite which is causative agent for sleeping sickness  in  human and nagana  in  animals,  conditions that  are  prevalence  in  sub  Saharan  Africa. In  this  study functional annotation and structure prediction of G.  M. morsitans odorant binding proteins was done by BLAST searches against NCBI and PDB databases respectively. Multiple sequence alignment was performed by clustalW while genetic  relatedness  of G.  m.  morsitans with  mosquitoes  (Anopheles  gambiae, Aedes  aegypti and Culex quinquefasciatus) and  fruit  fly  (Drosophila  melanogaster) was  determined  based  on  PHYML. The  3D-structure prediction  was  determined  and  viewed  using  Swiss  model  and Swiss-Pdb  Viewer  program  respectively. The GmmOBP9 had the highest percentage identity of 77.9% and e-value of 1.42e-10 with DroOBP83b as its ortholog. GmmOBP10 recorded the highest percentage identity among the mosquitoes studied having 60.23%, 57.65% and 62.35% for Anopheles, Aedes and Culex respectively. The lowest percentage identity of 27.4% and e-value of 0.04 was recorded for DroOBP56i by GmmOBP17 while GmmOBP3 recorded the lowest percentage identity among the mosquitoes  (Anopheles  and Aedes)  with  19.50%  and  24.06%  respectively.  The  Gmm-OBPs  had  amino  acid sequence length  ranging from  88 to  240  with  GmmOBP7  being  the  longest (240  aa  with MW  of 28.3kda  and pI 5.78).   GmmOBP20  had  the  lowest  MW  of  10.3  kda. The  GmmOBPs  had  a  theoretical  pI  range  of  4.41  to  9.30. Multiple  sequence  alignment  revealed  the  six  conserved  cysteine  while  phylogenetic  studies  indicate  that GmmOBPs  are  closely  related  to Drosophila OBPs.  Structural  prediction  of  the  GmmOBPs  showed  presence  of between  four  to  six  helices  with  multiple  alignments  with  respective  templates  confirming  the  location  of the conserved  six  cysteines.  This  study  predicts  the  three  dimensional  structure  of G.  m.  morsitans OBPs  and  open avenues for functional studies as they form potential targets for control of tsetse vectors. 

Key words: Glossina, olfaction, odorant binding protein