Table 1.

Binding free energy (in kcal/mol) calculations using the GBSW-GCS model for WT RecA and mutants to an anionic membrane.

System a	Mutations	ΔΔWslv b	ΔFbind c
WT //	-	−21.3 ± 2.3	−9.6 ± 0.9
WT ⊥	-	−13.6 ± 2.3	−5.0 ± 0.5
Mut1 //	Δ10N	−19.2 ± 4.0	−5.3 ± 0.6
Mut1 ⊥		−10.8 ± 1.4	−2.3 ± 0.1d
Mut2 //	I195A, R196A, K198A, I199A, V201A, F203A	−15.2 ± 6.7	−4.7 ± 2.9
Mut2 ⊥		−9.2 ± 1.3	−0.8 ± 0.1

^a. // and ⊥ refer to the parallel and perpendicular binding conformations (see Fig 2C,D), respectively.

^b. The vertical differential solvation free energy of the protein at the membrane surface vs. in bulk solution. As discussed in (Zhang et al., 2014), this quantity correlates with binding free energy when the system does not undergo significant conformational transitions upon binding.

^c. Binding free energy of the protein calculated using the protocol established in (Zhang et al., 2014) based on a specific thermodynamic cycle and the Bennett Acceptance Ratio (BAR) approach (Bennett, 1976).

^d. Mut1 for the perpendicular orientation leads to a 1.6 kcal/mol less binding free energy change than the parallel orientation. This is because the weakly perpendicularly bound RecA adjusts Loop L2 insertion to compensate the truncation of N-terminal amino acids to remain as the bound state. Meanwhile for parallel orientation, the change in insertion depth is negligible.