The Acanthamoeba SBDS, a cytoskeleton-associated gene, is highly expressed during phagocytosis and encystation

Background/Purpose: Shwachman-Bodian-Diamond syndrome (SBDS) protein is widely present in eukaryotes from vertebrates to protozoa. However, there are several variants within species, and previous studies have shown evidence that they may have additional functions. There are two SBDS-related proteins in Acanthamoeba. One is an rRNA metabolism protein of the SBDS family (ACA1_142090), and the other is SBDS (ACA1_204560). Although there is a conserved SBDS domain in the Acanthamoeba SBDS (ACA1_204560; AcSBDS), its function has not been reported. The aims of this study were to characterize the expression of AcSBDS during phagocytosis and encystation. Methods: AcSBDS-specific primer was designed to amplify the genomic AcSBDS of Acanthamoeba ATCC-30010. The AcSBDS expression was examined using reverse transcription polymerase chain reaction (RT-PCR) and immunostaining after phagocytosis and encystation treatment. Results: In this study, we found that the mRNA expression level of AcSBDS increased rapidly and that alternative splice variants were detected during phagocytosis and encystation processes. The results of immunofluorescence staining showed that the AcSBDS proteins accumulated surrounding phagocytosed bacteria. Conclusion: Our results suggest that AcSBDS may not only have ribosomal maturation features but also have cytoskeleton-associated functions related to phagocytosis and encystation.