Maltoporin

LamB porin
Structure of maltoporin from Salmonella typhimurium. [1]
Identifiers
Symbol	LamB
Pfam	PF02264
InterPro	IPR003192
SCOP2	2mpr / SCOPe / SUPFAM
TCDB	1.B.3
OPM superfamily	32
OPM protein	2mpr
CDD	cd01346
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary PDB 1a0s Q:97-505 1oh2 R:97-505 1a0t P:97-505 1mpr A:28-452 2mpr B:28-452 1mpm A:28-446 1mpo C:28-446 1af6 A:28-446 1mal C:28-446 1mpq B:28-446 1mpn B:28-446

Maltoporins (or LamB porins) are bacterial outer membrane proteins of the porin family. Maltoporin forms a trimeric structure which facilitates the diffusion of maltodextrins across the outer membrane of Gram-negative bacteria. The membrane channel is formed by an antiparallel beta-barrel. ^[2]

Most pores used for diffusion contain only 16 antiparallel strands, but maltoporin has 18. The structure of maltoporin contains long loops and short turns. The long loops are in contact with the cell exterior and the turns are in contact with the periplasm. This channel is involved in sugar transport. The sugar initially binds to the first greasy residue with van der Waals forces. The sugar continues through the channel by guided diffusion of the sugar along the greasy residues which form a "slide". ^[3]

Maltoporin's original name was LamB because it is a bacteriophage lambda receptor. This channel is specific for maltosaccharides, whose affinity for the channel increases as the length of the chain increases. ^[3]

References

1. Meyer JE, Hofnung M, Schulz GE (March 1997). "Structure of maltoporin from Salmonella typhimurium ligated with a nitrophenyl-maltotrioside". J. Mol. Biol. 266 (4): 761–75. doi:10.1006/jmbi.1996.0823. PMID   9102468.
2. Schirmer T, Rosenbusch JP, Keller TA, Wang YF (1995). "Structural basis for sugar translocation through maltoporin channels at 3.1 A resolution". Science. 267 (5197): 512–514. doi:10.1126/science.7824948. PMID   7824948. S2CID   44587780.
3. Ranquin, An; Van Gelder, Patrick (October 2004). "Maltoporin: sugar for physics and biology". Research in Microbiology. 155 (8): 611–616. doi: 10.1016/j.resmic.2004.05.007 .