characterization and phylogenetic analysis of a mitochondrial targeting alpha/beta hydrolase protein in strongyloides ratti

Strongyloides ratti is widely used as an experimental model for studying and diagnosing humans strongyloidiasis. the alpha/beta hydrolase domain proteins are ubiquitously distributed across all organisms. in this study, a 780-nucleotide cdna fragment was amplified by rt-pcr, and blast analysis revealed that 98.54% sequence identity with the only incomplete s. ratti mrna sequence available in genbank (xm_024652394.1). using this fragment as a probe, two expressed sequence tags (ests), 856 bp (fc815910.1) and 526 bp (bi742498.1), corresponding to the 3'and 5' ends, respectively, were identified and assembled into a full length cdna of 919 bp, designated srabh. its amino acid sequence exhibited 97.98% identity with the only available s. ratti sequence in genbank (xp_024505975.1). the molecular weight (mw) and isoelectric point (pi) of the protein are 33.484 kda and 7.18, respectively. signal peptide analysis indicated the absence of a secretion signal, however a mitochondrial targeting cleavage site was identified between amino acids 21-22. the highly conserved motif consists of nine amino acids spanning positions 111 to 120. the 3d structural analysis revealed that srabh consists of 9 alpha-helices (39.18%), 8 beta-sheets (18.21%), and loop regions  (42.61%). phylogenetic analysis clustered srabh with related nematode sequences, displaying by a high bootstrap support of 98. the lowest genetic distance (0.01%) was observed between srabh and the only sequence isolated from s. ratti (xp_024505975.1). given its molecular characteristics, this parasite's data may be valuable in structure-based drug design strategies using s. ratti as a model system for the human pathogen s. stercoralis.