Characterising ISWI chromatin remodeler in Trypanosoma cruzi

BACKGROUND Imitation SWItch (ISWI) ATPase is the catalytic subunit in diverse chromatin remodeling complexes. These complexes modify histone-DNA interactions and therefore play a pivotal role in different DNA-dependent processes. In Trypanosoma cruzi, a protozoan that controls gene expression principally post-transcriptionally, the transcriptional regulation mechanisms mediated by chromatin remodeling are poorly understood. OBJECTIVE To characterise the ISWI remodeler in T. cruzi (TcISWI). METHODS A new version of pTcGW vectors was constructed to express green fluorescent protein (GFP)-tagged TcISWI. CRISPR-Cas9 system was used to obtain parasites with inactivated TcISWI gene and we determined TcISWI partners by cryomilling-affinity purification-mass spectrometry (MS) assay as an approximation to start to unravel the function of this protein. FINDINGS Our approach identified known ISWI partners [nucleoplasmin-like protein (NLP), regulator of chromosome condensation 1-like protein (RCCP) and phenylalanine/tyrosine-rich protein (FYRP)], previously characterised in T. brucei, and new components in TcISWI complex [DRBD2, DHH1 and proteins containing a domain characteristic of structural maintenance of chromosomes (SMC) proteins]. Data are available via ProteomeXchange with identifier PXD017869. MAIN CONCLUSIONS In addition to its participation in transcriptional silencing, as it was reported in T. brucei, the data generated here provide a framework that suggests a role for TcISWI chromatin remodeler in different nuclear processes in T. cruzi, including mRNA nuclear export control and chromatin compaction. Further work is necessary to clarify the TcISWI functional diversity that arises from this protein interaction study.

pTcGW plasmid vectors 1.1 version: a versatile tool for Trypanosoma cruzi gene characterisation

The functional characterisation of thousands of Trypanosoma cruzi genes remains a challenge. Reverse genetics approaches compatible with high-throughput cloning strategies can provide the tool needed to tackle this challenge. We previously published the pTcGW platform, composed by plasmid vectors carrying different options of N-terminal fusion tags based on Gateway^® technology. Here, we present an improved 1.1 version of pTcGW vectors, which is characterised by a fully flexible structure allowing an easy customisation of each element of the vectors in a single cloning step. Additionally, both N and C-terminal fusions are available with new tag options for protein complexes purification. Three of the newly created vectors were successfully used to determine the cellular localisation of four T. cruzi proteins. The 1.1 version of pTcGW platform can be used in a variety of assays, such as protein overexpression, identification of protein-protein interaction and protein localisation. This powerful and versatile tool allows adding valuable functional information to T. cruzigenes and is freely available for scientific community.