Taken together, our results establish a mechanism for how mitotic proteins Bub3 and BuGZ functions in transcriptional regulation in a eukaryotic organism. The deposition of BuGZ along cat-3 chromatin hindered the recruitment of transcription activators GCN4/CPC1 and NC2 complex, thereby preventing the assembly of the transcriptional machinery. However, the zinc finger domains of BuGZ have no effects on DNA binding, although mutations of these highly conserved domains lead to loss of cat-3 repression. Further experiments demonstrated that BuGZ binds directly to the cat-3 gene and responses to cat-3 overexpression induced by oxidative stresses. Despite loss of the interaction, the amount of BuGZ mutant protein negatively correlated with the cat-3 expression level, indicating that BuGZ amount rather than Bub3-BuGZ interaction determines cat-3 transcription level. Our data indicate that BuGZ and Bub3 interact directly via the GLEBS domain of BuGZ. The absence of Bub3 caused a significant decrease in BuGZ protein levels. Here, we demonstrate that Bub3 and BuGZ negatively regulate cat-3 transcription in the model filamentous fungus Neurospora crassa. In aerobic organisms, transcriptional regulation of catalase genes in response to developmental or environmental stimuli is necessary for redox homeostasis. They undergo rapid polymerization and depolymerisation.The spindle assembly checkpoint factors Bub3 and BuGZ play critical roles in mitotic process, but little is known about their roles in other cellular processes in eukaryotes. The microtubules in spindle apparatus are mainly involved in separation of sister chromatids. Note: Spindle apparatus is involved in separation of chromosomes and its formation begins in prometaphase and binds to sister chromatids in metaphase. The division of cytoplasm begins with contraction of contractile rings. Nuclear membranes start to reform around them. In Telophase, two sets of daughter chromosomes arrive at poles of spindle and decadence. This process occurs because of rapid polymerization and depolymerisation of microtubules in spindle fibres. In this phase, replicated chromosomes are split and the newly-copied chromosomes (sister chromatids) are moved to opposite poles of the cell. The kinetochores microtubules get shortened and chromosome segregation occurs.ДЄnaphase, the stage of mitosis, occurs after the process of metaphase. In anaphase, the sister chromatids separate to form two daughter chromosomes and each is pulled toward the spindle pole. The kinetochore microtubules attach sister chromatids to opposite poles of the spindle. In metaphase, chromosomes are aligned at the equator of the spindle, midway between spindle poles. Other spindle microtubules make contact with microtubules coming from the opposite pole. Kinetochore microtubules emerging from the centrosomes at the ends of the spindle reach the chromosomes and attach to the kinetochores. The chromosomes inside form protein structures called kinetochores. The spindle apparatus attach to the centromere and undergo active movement. Formation of spindle apparatus occurs during this stage. Prometaphase starts abruptly with breakdown of nuclear membrane. It is the most important event of prophase. Prophase starts with condensation of chromosomes into sister chromatids. The stages are prophase, prometaphase, metaphase, anaphase, Telophase and finally cytokinesis. The mitotic cell division is carried out in various stages. It is the characteristic features of eukaryotic cells. Spindle apparatus is formed from centromere present in cell cytoplasm. Hint: Spindle apparatus is responsible for separation of chromosomes during cell division.