STRUCTURE OF MALTOPORIN FROM SALMONELLA-TYPHIMURIUM LIGATED WITH A NITROPHENYL-MALTOTRIOSIDE

The maltodextrin-specific (malto-)porin from Salmonella typhimurium ha s been crystallized. Its three-dimensional structure was determined at 2.4 Angstrom resolution (1 Angstrom = 0.1 nm). A comparison with the structure of the homologous porin from Escherichia coli as well as wit h the sequences of other related porins showed that there are regions of appreciable sequence and structure variability, despite close overa ll similarity. The maltoporin structure was analyzed with a bound nitr ophenyl-maltotrioside as well as without ligand. Maltotrioside binding had a negligible effect on the polypeptide structure. It binds at the pore eyelet assuming a conformation close to the natural amylose heli x. (C) 1997 Academic Press Limited.