TABLE 1.

Pairs of residues identified by interface alanine scanning as making significant energetic contributions to E1/E2 binding free energy^a

Interaction	E1 residue(s)	ΔΔG for E1 (complex)	E2 residue(s)	ΔΔG for E2 (complex)
Hydrophobic	Leu 265	2.48	Leu 675	1.12
	Trp 320	2.64	Trp 672	3.82
	Val 374	1.35	Leu 735	1.08
Charged or polar	Arg 195, Asp 279	4.20, 4.04
	Arg 260	1.82	Tyr 632, Glu 637	1.75, 1.40
	Thr 300	1.43	Leu 546	2.05
	Asp 303	1.65	Asn 577	2.50
	Asn 325	0.80	Arg 587	2.06
	His 352	1.26	Asp 658	1.41

^aThe third and fifth columns give the changes in Rosetta scores for the E1/E2 interaction resulting from mutation of E1 and E2 residues, respectively, to Ala, compared to the E1/E2 interaction energy for the wild-type proteins. A positive value indicates that the mutation destabilizes the interaction between E1 and E2.