1,10-phenanthroline inhibits sumoylation and reveals that yeast SUMO modifications are highly transient.

The steady-state levels of protein sumoylation depend on relative rates of conjugation and desumoylation. Whether SUMO modifications are generally long-lasting or short-lived is unknown. Here we show that treating budding yeast cultures with 1,10-phenanthroline abolishes most SUMO conjugations within one minute, without impacting ubiquitination, an analogous post-translational modification. 1,10-phenanthroline inhibits the formation of the E1~SUMO thioester intermediate, demonstrating that it targets the first step in the sumoylation pathway. SUMO conjugations are retained after treatment with 1,10-phenanthroline in yeast that express a defective form of the desumoylase Ulp1, indicating that Ulp1 is responsible for eliminating existing SUMO modifications almost instantly when de novo sumoylation is inhibited. This reveals that SUMO modifications are normally extremely transient because of continuous desumoylation by Ulp1. Supporting our findings, we demonstrate that sumoylation of two specific targets, Sko1 and Tfg1, virtually disappears within one minute of impairing de novo sumoylation. Altogether, we have identified an extremely rapid and potent inhibitor of sumoylation, and our work reveals that SUMO modifications are remarkably short-lived.

Fabrication of complex patterns with a wide range of feature sizes from a single line prepattern by successive application of capillary force lithography.

The variously shaped gold patterns can be generated from the polydimethylsiloxane (PDMS) mold using line patterns by the capillary force lithography (CFL) process, which is a kind of nanoimprint method following the two-cycle method. After fabrication of micro- or nanosized line patterns at the first cycle, the patterned substrate is used as a substrate for the second cycle of CFL. When the other stamp is placed on the first pattern, rotated by a certain angle with respect to the first stamp, only the overlapped parts remained dot-shaped after the etching process. The various shapes and sizes of patterns can be produced by controlling the CFL conditions such as polymer thickness, reactive ion etching (RIE) time, and degree of rotation angle. The key advantage of the double imprint lithography method is to get the nanosized isolated dot-shaped patterns from microsized line patterns. If we fabricate nanosized isolated dot-shaped patterns directly, we should need predesigned patterns in the form of a master, which is generally prepared by a high-cost and time-consuming process such as E-beam lithography. The successful applications of large-area periodic patterns are nanoelectronic devices, nanoelectromechanical system (NEMS), and biosensors, the template of which is the master of nanoimprint lithography (NIL) and stamp fabrication in soft lithography.