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Abstract Human African trypanosomosis (HAT) and animal African trypanosomosis (AAT) are diseases of economic importance in humans and animals that affect more than 36 African countries. The currently available trypanocidal drugs are associated with side effects, and the parasites are continually developing resistance. Thus, effective and safe drugs are needed for the treatment of HAT and AAT. This study aimed to evaluate the effects of azithromycin (AZM) on Trypanosoma brucei brucei -infected mice. Mice were randomly divided into 7 groups consisting of a vehicle control group, 5 test groups and a diminazene aceturate (DA)-treated group. Mice were treated orally for 7 and 28 days, as short-term and long-term treatments, respectively. Short-term AZM treatment cured 23% (16 of 70) of the overall treated mice whereas long-term treatment resulted in the survival of 70% of the mice in the groups that received AZM at doses of 300 and 400 mg/kg. Trypanosomes treated in vitro with 25 μg/mL of AZM were subjected to transmission electron microscopy, which revealed the presence of increased numbers of glycosomes and acidocalcisomes in comparison to the vehicle group. The current study showed the trypanocidal effect of AZM on T. b. brucei in vivo. The demonstrated efficacy increased with an increase in treatment period and an increased concentration of AZM. Graphical abstract Image 1 Highlights • Azithromycin (AZM) possesses trypanocidal activity against Trypanosoma brucei brucei in vivo. • The efficacy of orally administered AZM in T. b. brucei- infected mice is dose and treatment duration dependent. • AZM induces external stress on T. b. brucei cells in vitro. [ABSTRACT FROM AUTHOR]

Abstract: Glycosomes are peroxisome-like organelles essential for trypanosomatid parasites. Glycosome biogenesis is mediated by proteins called “peroxins,” which are considered to be promising drug targets in pathogenic Trypanosomatidae. The first step during protein translocation across the glycosomal membrane of peroxisomal targeting signal 1 (PTS1)-harboring proteins is signal recognition by the cytosolic receptor peroxin 5 (PEX5). The C-terminal PTS1 motifs interact with the PTS1 binding domain (P1BD) of PEX5, which is made up of seven tetratricopeptide repeats. Obtaining diffraction-quality crystals of the P1BD of Trypanosoma brucei PEX5 (TbPEX5) required surface entropy reduction mutagenesis. Each of the seven tetratricopeptide repeats appears to have a residue in the αL conformation in the loop connecting helices A and B. Five crystal structures of the P1BD of TbPEX5 were determined, each in complex with a hepta- or decapeptide corresponding to a natural or nonnatural PTS1 sequence. The PTS1 peptides are bound between the two subdomains of the P1BD. These structures indicate precise recognition of the C-terminal Leu of the PTS1 motif and important interactions between the PTS1 peptide main chain and up to five invariant Asn side chains of PEX5. The TbPEX5 structures reported here reveal a unique hydrophobic pocket in the subdomain interface that might be explored to obtain compounds that prevent relative motions of the subdomains and interfere selectively with PTS1 motif binding or release in trypanosomatids, and would therefore disrupt glycosome biogenesis and prevent parasite growth. [Copyright &y& Elsevier]

Abstract: The glycosomes of trypanosomatids are essential organelles that are evolutionarily related to peroxisomes of other eukaryotes. The peroxisomal RING proteins—PEX2, PEX10 and PEX12—comprise a network of integral membrane proteins that function in the matrix protein import cycle. Here, we describe PEX10 and PEX12 in Trypanosoma brucei, Leishmania major, and Trypanosoma cruzi. We expressed GFP fusions of each T. brucei coding region in procyclic form T. brucei, where they localized to glycosomes and behaved as integral membrane proteins. Despite the weak transmembrane predictions for TbPEX12, protease protection assays demonstrated that both the N and C termini are cytosolic, similar to mammalian PEX12. GFP fusions of T. cruzi PEX10 and L. major PEX12 also localized to glycosomes in T. brucei indicating that glycosomal membrane protein targeting is conserved across trypanosomatids. [Copyright &y& Elsevier]