Structural comparison of tRNA m1A58 methyltransferases revealed different molecular strategies to maintain their oligomeric architecture under extreme conditions

Table 3 Dimeric and tetrameric contacts in TrmI proteins.

	A/B dimer							A/C dimer							Tetrameric assembly
structures	N° of interfacing residues in both partners	Interface area (Å ² )	Buried surface area (Å ² )	N _HB ¹	N _SB ²	N _vdW ³	hydrophobic P -value ⁴	N° of interfacing residues in both partners	Interface area (Å ² )	Buried surface area (Å ² )	N _HB ¹	N _SB ²	N _vdW ³	hydrophobic P -value ⁴	Buried surface area (Å ²⁾	ΔGint ⁵ kcal/mol	ΔGdiss ⁶ kcal/mol
M. tuberculosis	76+75	2378.4	4760	28	6 (0)	30	0.299	23+23	788.7	1580	10	4 (2)	10	0.22	13160	-69.5	24.7
T. thermophilus	95+62	2478.1	4960	21	18 (5)	30	0.776	22+22	731.3	1460	12	4 (2)	13	0.423	13390	-25.9	20.8
T. maritima	87+87	3150.2	6160	24	36 (4)	103	0.356	24+24	879.5	1810	10	4 (2)	22	0.668	16750	-47.9	3.0
A. aeolicus	65+65	2596.3	5200	34	14 (0)	44	0.059	22+24	856.5	1710	12	4 (2)	4	0.416	14410	-54.7	15.1
P. abyssi	65+65	2311.5	4620	17	14 (6)	30	0.006	24+24	775.6	1550	12	0	10	0.069	12840	-86.6	41.0

¹Number of H-bonds less than 3.2 Å across the interface (per monomer).
²Number of salt bridges less than 3.6 Å across the interface (per monomer). The number of bidentate ionic interactions is indicated in parentheses.
³Number of van der Waals interactions less than 4.2 Å (per monomer)
⁴defined as the probability to find a same-area patch on protein surface that would be more hydrophobic than the interface
⁵solvation free energy gain upon formation of the assembly
⁶free energy difference between dissociated and associated states

ISSN: 1472-6807