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Biology subjects

Seshan, A.

Publications and source records attributed to Seshan, A..

2 recordsLinked to original sources

A simple, robust, broadly applicable insertion mutagenesis method to create random fluorescent protein - target protein fusions.

A simple broadly applicable method was developed using an in vitro transposition reaction followed by transformation into Escherichia coli and screening plates for fluorescent colonies. The transposition reaction catalyzes the random insertion of a fluorescent protein open reading frame into a target gene on a plasmid. The transposition reaction is employed directly in an E. coli transformation with no further procedures. Plating at high colony density yields fluorescent colonies. Plasmids purified from fluorescent colonies contain random, in-frame fusion proteins into the target gene. The plate screen also results in expressed, stable proteins. A large library of chimeric proteins was produced that was useful for downstream research. The effect of using different fluorescent proteins was investigated as well as the dependence of linker sequence between the target and fluorescent protein open reading frames. The utility and simplicity of the method was demonstrated by the fact that it has been employed in an undergraduate biology laboratory class without failure over dozens of class sections. This suggests that the method will be useful in high impact research at small liberal arts colleges with limited resources. However, in frame fusion proteins were obtained from eight different targets suggesting that the method is broadly applicable in any research setting. SummaryThis report describes a simple screen to obtain random insertions of fluorescent proteins into a target protein of interest. The screen results in a useful library of mutated and functional tagged proteins that can be employed to investigate protein biochemical activity, protein structure, protein function and protein cellular localization. The screen is robust, generally applicable, and has been employed in an undergraduate laboratory class. It is also useful for studies in advanced research-intensive projects carried out in institutions of all types. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=119 SRC="FIGDIR/small/578020v1_ufig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@22dc94org.highwire.dtl.DTLVardef@bf789dorg.highwire.dtl.DTLVardef@87c53forg.highwire.dtl.DTLVardef@1a6c0e9_HPS_FORMAT_FIGEXP M_FIG C_FIG

genetics↗

BFA1 has multiple positive roles in directing late mitotic events in S. cerevisiae

The proper regulation of cell cycle transitions is paramount to the maintenance of cellular genome integrity. In budding yeast, the mitotic exit network (MEN) is a Ras-like signaling cascade that effects the transition from M phase to G1 during the cell division cycle in budding yeast. MEN activation is tightly regulated. It occurs during anaphase and is coupled to mitotic spindle position by the spindle position checkpoint (SPoC). Bfa1 is a key component of the SPoC and functions as part of a two-component GAP complex along with Bub2. The GAP activity of Bfa1-Bub2 keeps the MEN GTPase Tem1 inactive in cells with mispositioned spindles, thereby preventing inappropriate mitotic exit and preserving genome integrity. Interestingly, a GAP-independent role for Bfa1 in mitotic exit regulation has been previously identified. However the nature of this Bub2-independent role and its biological significance are not understood. Here we show that Bfa1 also activates the MEN by promoting the localization of Tem1 primarily to the daughter spindle pole body (dSPB). We demonstrate that the overexpression of BFA1 is lethal due to defects in Tem1 localization, which is required for its activity. In addition, our studies demonstrate a Tem1-independent role for Bfa1 in promoting proper cytokinesis. Cells lacking TEM1, in which the essential mitotic exit function is bypassed, exhibit cytokinesis defects. These defects are suppressed by the overexpression of BFA1. We conclude that Bfa1 functions to both inhibit and activate late mitotic events.

genetics↗