This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our studies with non-annotated ORFs allowed us to identify a novel gene required for cell cycle progression in yeast S. cerevisiae that we named as EFG1. S. cerevisiae cells lacking EFG1 showed a delay in cell cycle progression from the G1 phase to the S phase (hence the name EFG1 for Exit From G1). EFG1 was not previously annotated due to an error in the reported sequence in the genome. Western blot analysis confirmed expression of the C-terminally tagged Efg1p-HA throughout the cell cycle with a predicted MW of 42 kDa.. In order to gain further insights into the functional mechanism of EFG1 in S. cerevisiae, we have taken several genetic and biochemical approaches. Our results showed that in addition to the above observed cell cycle progression defect, efg1 strain also showed slow growth phenotype as well as temperature sensitivity (ts; 37C), cold sensitivity (cs; 15C) and sensitivity to a DNA replication arrest agent hydroxyurea (HU). efg1 strain did not however show distinguishable sensitivity to the DNA damage agents bleomycin, MMS and 4NQO. Since efg1 strain showed a very tight cs phenotype among all its known phenotypes, we attempted to identify over-expression suppressors of its cs phenotype. These studies allowed isolation of several candidate suppressors further investigation of which should shed light onto the function of EFG1. We have also initiated a synthetic genetic analysis (SGA) with efg1 and propose to do a yeast two-hybrid analyses to gain further insights into the role of EFG1 in cell cycle progression.
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