Characterization of RAB-like4, the first identified RAB-like protein from Trypanosoma cruzi with GTPase activity

RAB proteins, which belong to the RAS superfamily, regulate exocytic and endocytic pathways of eukaryotic cells, controlling vesicle docking and fusion. Few RAB proteins have been identified in parasites. Molecular markers for cellular compartments are important to studies concerning about the protein traffic in Trypanosoma cruzi, the causal agent of Chagas disease. in this work, we describe the characterization of TcRABL4, the first RAB-like gene identified in T. cruzi (GenBank Accession No.: AY371275), present as a single-copy gene. TcRABL4 contains all five consensus RAB motifs but lacks cysteine residues at the C terminus, which are essential to isoprenylation, an absolute prerequisite for membrane association of these proteins. TcRABL4 is a functional GTPase that is able to bind and hydrolyze GTP, and its gene is transcribed as a single 1.2 kb mRNA in epimastigotes. TcRABL4 appears to be differentially regulated in the three cell forms of the parasite, and the protein is not associated to membranes, unlike other RAB proteins. It is possible that TcRABL4 may be a member of a novel family of small GTPases. (c) 2005 Elsevier Inc. All rights reserved.Univ Fed Rio de Janeiro, CCS, Inst Biofis Carlos Chagas Filho, Lab Metab Macromol Firmino Torres Castro, BR-21949900 Rio de Janeiro, BrazilUniv Fed Rio de Janeiro, Dept Clin Med, BR-21949900 Rio de Janeiro, BrazilUniv Fed Rio de Janeiro, CCS, Inst Biofis Carlos Chagas Filho, Lab Ultraestrutura Cellular Hertha Meyer, BR-21949900 Rio de Janeiro, BrazilUniv Fed Rio de Janeiro, CCS, Inst Bioquim Med, Lab Membranes Transportadoras, BR-21941590 Rio de Janeiro, BrazilUNIFESP, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilUNIFESP, Escola Paulista Med, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilWeb of Scienc