Malaria is one of the most deadly infectious parasitic diseases, which affected over and above 241 million individuals and 627,000 deaths in 2020 (WHO malaria report 2021). Presently, malaria treatment relies heavily on chemotherapeutics and chemoprophylaxis because of limitations in vaccine development and vector control. The reason behind the illness and death from malaria is the development of resistance to available antimalarial drugs. Due to the development of multi-drug resistance, eradication of malaria demands the finding of novel drugs and drugs against novel drug targets (Visser et al., 2014; Haldar et al., 2018; Shibeshi and Kifle, 2020).

In malaria parasite, numbers of proteins are involved in malaria pathogenesis. They are responsible for the maintenance of parasite biology. Among them, some are act as antimalarial drug targets, responsible for resistance development and also as vaccine candidates. But there are also a number of proteins that are not characterized by their functions and importance; maybe they have the potential for use as a target for the synthesis of new antimalarials. To find new target for parasites, we have performed the microarray analysis of rodent malaria parasites and found some uncharacterized proteins. Among them, Calcyclin binding protein is still uncharacterized in regard to malaria and other parasitic diseases (Unpublished data).

Calcyclin binding protein (CacyBP) was first discovered in cytosolic fraction of Ehrlich ascites tumor cells and further in insect Apis cerana cerana (Filipek and Wojda, 1996; Yu et al., 2012). Calcyclin binding protein is also known as Siah-1 interacting protein (SIP) (Filipek and Wojda, 1996; Matsuzawa and Reed, 2001). CacyBP/SIP interacts with various S100 families, such as S100A1, S100A12, SKP-1 (S-phase kinase-associated protein1), tubulin, ERK1/2 (extracellular signal-regulated kinases 1 and 2) (Filipek et al., 2002; Kilanczyk et al., 2009; Schneider et al., 2010; Jurewicz et al., 2013). CacyBP/SIP has a significant role in many cellular functions for example, differentiation, cytoskeleton organization, ubiquitination, proliferation, apoptosis, tumorigenesis and transcription regulation through interaction with target proteins (Schneider and Filipek, 2011; Topolska-Woś et al., 2016). CacyBP/SIP has some sequence homology with SGT1, an Hsp90 co-chaperone, suggesting that CacyBP/SIP is involved in regulating Hsp90 chaperone machinery (Bhattacharya et al., 2005; Filipek et al., 2007; Góral et al., 2016).

In this study, we have selected the rodent species of malaria parasite Plasmodium yoelii nigeriensis for the characterization of CacyBP. Here, we have cloned and sequenced the CacyBP gene. After that, we overexpressed and purified the CacyBP for molecular and biophysical characterization. PyCacyBP-specific humoral and cellular immune responses were also analyzed.