Identification of Potential Substrates for the Enzyme Sortase in the Human Genome

Background: Sortase is a bacterial enzyme which ligates a protein to the membrane. Thebacterial surface proteins are produced as immature proteins in the cytoplasm and contain asignal peptide and a soratase-recognition motif (LPXTG) at the amine and carboxyl terminals,respectively. After expression, the proteins directed out of the cytoplasm by the Sec secretorysystem. After cleavage of the signal, proteins remain attached to the membrane by thehydrophobic motif. By identifying the LPXTG sequence, the enzyme sortase breaks down somebonds and makes new bonds that results in the protein binding to the cell surface. The aim of thisstudy is to find out the presence of an LPXTG motif in human proteins. These proteins canpotentially be sortase substrates.Materials and Methods: To find out all putative sortase substrates for our future investigations,genome-wide screening was done in the resource of “scan prosite” in the www.expasy.orgwebsite. The search for proteins with this motif was done separately for each amino acid in the Xposition.Results: We extracted ۱۸۴ human protein types with LPXTG motif in their sequences. Theseproteins were classified via their subcellular locations and ۱۳ membrane protein types wereselected in which the motif was located on the extracellular surface.Conclusion: In previous works it was shown that glutamic acid (E) is the most frequent aminoacid presented in the X position in the bacteria but in the human genome the frequency ofargenin (A) in this position is more than other amino acids.

کلیدواژه ها:

sortase ، human genome ، surface protein