An In Silico Approach for Function Prediction of Hypothetical Proteins of Listeria monocytogenes

Abstract

L monocytogenes, a gram-positive facultative intracellular bacterium, is an opportunistic pathogen for animals and humans. It causes a disease called listeriosis. A peculiar property of L. monocytogenes that affects its food-borne transmission is the ability to multiply at low temperatures. The bacterium L. monocytogenes is a proposed vaccine carrier. Total proteins in Listeria monocytogenes are 2846. Out of this, 512 proteins are hypothetical and functions of 2334 proteins were already known. Total no. of RefSeq hypothetical proteins were 436 which were needed to annotate. Lack of sequence similarity in the database to the protein of interest creates difficulties for functional predictions. By a combination of different in silico approaches such as sequence similarity search using PSI-BLAST; domain searching using InterProScan, Pfam, CDD; Secondary fold annotation using PHYRE; 3D homology model search using Metaserver; and final biological function confirmation using PFP, ProtFun, TMHMM; functions were predicted of 432 proteins and only 4 proteins are remain unannotated. From this work, it is predicted that these bacteria are having protein called Aryldialkylphosphatase which can degrade agricultural pesticides such as parathion. This work would also be helpful to understand metabolism and another functional role of the organism.