Acceleration of Protein Degradation by 20S Proteasome-Binding Peptides Generated by In Vitro Artificial Evolution.

Although the 20S core particle (CP) of the proteasome is an important component of the 26S holoenzyme, the stand-alone 20S CP acts directly on intrinsically disordered and oxidized/damaged proteins to degrade them in a ubiquitin-independent manner. It has been postulated that some structural features of substrate proteins are recognized by the 20S CP to promote substrate uptake, but the mechanism of substrate recognition has not been fully elucidated. In this study, we screened peptides that bind to the 20S CP from a random eight-residue pool of amino acid sequences using complementary DNA display an in vitro molecular evolution technique. The identified 20S CP-binding amino acid sequence was chemically synthesized and its effects on the 20S CP were investigated. The 20S CP-binding peptide stimulated the proteolytic activity of the inactive form of 20S CP. The peptide bound directly to one of the α-subunits, opening a gate for substrate entry on the α-ring. Furthermore, the attachment of this peptide sequence to α-synuclein enhanced its degradation by the 20S CP in vitro. In addition to these results, docking simulations indicated that this peptide binds to the top surface of the α-ring. These peptides could function as a key to control the opening of the α-ring gate.

Assessment of the Physical Invasiveness of Peroral Endoscopic Myotomy during the Perioperative Period Based on Changes in Energy Metabolism.

A novel treatment method for achalasia of the esophagus and related disorders is known as peroral endoscopic myotomy (POEM). This study aimed to calculate the resting energy expenditure (REE) and evaluated the degree of physical invasiveness based on metabolic changes during the perioperative period of POEM. Fifty-eight patients who underwent POEM were prospectively enrolled; REE, body weight (BW), and basal energy expenditure were measured on the day of POEM, postoperative day 1 (POD 1), and three days after POEM (POD 3). The median REE/BW increased from 19.6 kcal/kg on the day of POEM to 24.5 kcal/kg on POD 1. On POD 3, it remained elevated at 20.9 kcal/kg. The stress factor on POD 1 was 1.20. Among the factors, including the Eckardt score, operation time, and the length of myotomy, the length of myotomy was associated with changes in REE/BW. During the perioperative period of POEM, the level of variation in energy expenditure was lower than that of esophageal cancer surgeries performed under general anesthesia. However, because the length of myotomy is a factor affecting changes in energy expenditure, careful perioperative management is desirable for patients with longer myotomy lengths.