Anion-selective Formate/nitrite transporters: taxonomic distribution, phylogenetic analysis and subfamily-specific conservation pattern in prokaryotes

Table 1 Group conservation of small and weakly polar residues at the helix-helix interface of all FNT channels^a

Residue^b	Location in the channel	Residues in the position^c	Conservation (%)^d
A38 (TM1)	TM1-TM3 interface	A(46), S, G	98.2
A41 (TM1)	TM1-Ω interface	A(81), G, S	99.2
G42 (TM1)	TM1-TM3 interface	G(95), C, S	99.6
S46 (TM1)	TM1-TM3 interface	G(38), A, S, T	97.5
A48 (TM1)	TM1-TM2a interface	G(44), A(31), S, T	95.6
G72 (TM2a)	TM2a-TM5a interface	G(43), A(36), S	89.8
G78 (TM2a)	TM1-TM2a interface	G(78), A, S	99.7
G120 (TM3)	TM1-TM3 interface	G(71), A, S, C, T	87.3
G124 (TM3)	TM1-TM3 interface	G(99)	99.9
A125 (TM3)	TM1-TM5b interface	A(45), G, S, T, C	97.4
V129 (TM3)	TM1-TM5b interface	A(62), G, S, C, T	76.8
G168 (TM4)	TM4-TM6 interface	G(69), A, S	100.0
C176 (TM4)	TM4-TM6/Ω interface	C(55), A, S, G, T	89.5
A178 (TM4)	TM4-TM5a interface	A(60), S, G	79.9
G220 (S-loop)	TM1-TM5b interface	G(42), S, A, T	78.8
G261 (TM6)	TM4-TM6 interface	G(99)	99.4
G265 (TM6)	TM4-TM6 interface	G(95), S, A	99.9
G266 (TM6)	Ω-TM6 interface	G(97), A	100.0
G271 (TM6)	Ω-TM6 interface	G(56), A, T, S, C	94.7

^aAll 2206 FNT channels from bacteria, archaea and eukaryotes were considered for this analysis
^bResidue numbers correspond to that of formate channel structure as available in the PDB ID: 3KCU. Occurrence of these residues in the transmembrane segments or the functionally important loop region is also provided
^cPercentage conservation of the most frequently observed residue(s) is indicated in brackets
^dPercentage conservation as observed in all 2206 FNT channels

ISSN: 1471-2164