id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-269707-titu9lm4	Hsieh, Ching-Lin	Structure-based design of prefusion-stabilized SARS-CoV-2 spikes	2020-07-23		.txt	text/plain	2125	122	50	Here, we characterized 100 structure-guided spike designs and identified 26 individual substitutions that increased protein yields and stability. Testing combinations of beneficial substitutions resulted in the identification of HexaPro, a variant with six beneficial proline substitutions exhibiting ~10-fold higher expression than its parental construct and the ability to withstand heat stress, storage at room temperature, and three freeze-thaw cycles. High-yield production of a stabilized prefusion spike protein will accelerate the development of vaccines and serological diagnostics for SARS-CoV-2. In addition to salt bridges, filling loosely packed hydrophobic cores that allow the protein to refold can help stabilize the prefusion state, as shown by previous cavity-filling substitutions in RSV F and HIV-1 Env (12, 20, 22) . Adding one disulfide (S884C/A893C) to a single proline variant (F817P) also reduced the expression level, although the quaternary structure of the spikes was well maintained (table S2, Combo40). HexaPro expressed 9.8-fold higher than S-2P, had ~5°C increase in Tm, and retained the trimeric prefusion conformation (Fig. 3D) .	./cache/cord-269707-titu9lm4.txt	./txt/cord-269707-titu9lm4.txt