Facilitate Chromatin Transcription Complex Subunit Pob3 Regulates Sexual Reproduction in Tetrahymena thermophila
CHEN Hongyu1, XU Jing1,2, BO Tao1, LIAN Yinjie1, HAO Huijuan1, WANG Wei1*
The FACT (facilitate chromatin transcription) complex is involved in chromatin remodeling during transcription, replication, and DNA repair. FACT contains two subunits: POB3/SSRP1 (structure-specific recognition protein-1) and SPT16 (suppressor of Ty 16). Although the function of the complex has been studied in fungi, plants, and animals, it′s function is not completely clear. Tetrahymena thermophila contains two different nucleus and changes chromatin structure during sexual development stage. In the study, we found POB3 expressed at a lower level in the vegetative growth stage and starvation stage, and highly expressed throughout conjugation stage in T. thermophila. HA-Pob3 localized in the parental macronucleus and micronucleus during the growth and starvation stage and localized in the new macronuclei and micronuclei during sexual developmental stage. Micronuclear stainning was stronger than macronuclear signal through sexual developmental stage. Truncated HA-Pob3Δ33 localized in the cytoplasm in the early sexual reproduction, but occurred in the selected gametic nuclei and new macronuclei in the late sexual reproduction. Truncated HA-Pob3Δ87 localized only in the cytoplasm throughout sexual reproduction stage. POB3 knockdown mutants failed to complete gametic mitosis and zygotic mitosis, which aborted sexual reproduction progress. The results showed that Pob3 regulated nuclear mitosis and was required for normal sexual reproduction progress in T. thermophila.
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