- High Dosage of Rok1p, a Putative ATP-dependent RNA Helicase, Leads to a Cell Cycle Arrest at G1/S Stage in Saccharomyces cerevisiae
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jeong, Hyun Sook , Oh, Jae Young , Kim, Jin Mi
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J. Microbiol. 1998;36(2):139-144.
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 Abstract
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The ROK1 gene encodes a putative ATP-dependent RNA helicase which is essential for mitotic cell growth. ROK1 has been thought to affect microtubule and spindle pole body (SPB) functions in Saccharomyces cerevisiae. To investigate the intracellular functions of ROK1, we varied the Rok1 protein dosage in a cell and analyzed its phenotypic effects. Overexpression of the ROK1 gene by using a strong GAL1 promoter was lethal, leading cells to arrest at the unbudded stage. This arrest phenotype is very similar to that of the rok1 null mutation. Indirect immunofluorescence revealed that the majority of arrested cells contained a single SPB. Normas development of microtubules between the duplicated SPSs was rarely observed. Multinuclear cells with abnormal microtubule array were detected in small fraction. Taken together with the phenotype of the rlk1 null mutation, these results imply that ROK1 is required for cell cycle progression at the G1/S stage.
- A conditional lethal mutation of a nucleoporin gene, NUP49 in saccharomyces cerevisiae
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Lee, Youn Soo , Song, Young Ja , Hwang, Mi Kyung , Lee, Woo Bok , Kim, Jin Mi
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J. Microbiol. 1997;35(3):234-238.
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Conditional lethal mutation nup49-1 of a nuclear pore complex component gene was constructed in Saccharomyces cerevisiae. This mutation deleted one third of the essential NUP49 gene at the carboxy-terminal, but retained 13 repeats of the highly conserved GLFG domain. The nup49-1 mutant strain was viable with a slow-growth phenotype, indicating that the C-terminal is dispensable at normal growth temperature. This strain exhibited both temperature-sensitivity at 37℃ and cold-sensitivity at 16℃. Temperature shift experiments revealed that the arrest phenotype at 37℃ was random in the cell division cycle. The nup49-1 mutation was tested to be recessive and is expected to be useful for the functional analysis of nuclear pore complex proteins as well as for studies of nuclear transport systems.
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