Characterization of a novel amastin-like surface protein (ALSP) of Leishmania donovani, a probable lipase

Abstract

In the current study, a novel putative protein of Leishmania donovani, amastin-like surface protein (ALSP) has been characterized. The gene was cloned in a bacterial system and the protein was overexpressed. A polyclonal antibody was developed against the protein, which detected a 10 kDa band in the L. donovani amastigote. ALSP mRNA was detected in L. donovani amastigote, which was not expressed in the promastigote. ALSP mRNA was not expressed in either morphological forms of Leishmania major. MALDI-TOF confirmed the molecular weight of ALSP as 10 kDa. I-TASSER predicted the function of ALSP as a lipase, which was confirmed by preliminary in-vitro experiments using amastigotes of L. donovani. ALSP has GAS amino acid sequences, which might act as the active site for its lipase activity. The selective expression of ALSP in amastigotes probably makes it important in virulence mechanisms such as survival in the phagolysosome and modulation of its membrane and other metabolic functions, necessary for parasite survival in the human host. ALSP can act as a peptide vaccine target and maybe detected in the peripheral blood or urine as a molecular biomarker of active disease in visceral leishmaniasis.