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Crystal structure of the bacterial nucleoside transporter Tsx
Author(s) -
Ye Jiqing,
van den Berg Bert
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600330
Subject(s) - nucleoside , biology , escherichia coli , biochemistry , bacterial outer membrane , binding site , nucleotide , membrane transport protein , stereochemistry , membrane , membrane protein , chemistry , gene
Tsx is a nucleoside‐specific outer membrane (OM) transporter of Gram‐negative bacteria. We present crystal structures of Escherichia coli Tsx in the absence and presence of nucleosides. These structures provide a mechanism for nucleoside transport across the bacterial OM. Tsx forms a monomeric, 12‐stranded β‐barrel with a long and narrow channel spanning the outer membrane. The channel, which is shaped like a keyhole, contains several distinct nucleoside‐binding sites, two of which are well defined. The base moiety of the nucleoside is located in the narrow part of the keyhole, while the sugar occupies the wider opening. Pairs of aromatic residues and flanking ionizable residues are involved in nucleoside binding. Nucleoside transport presumably occurs by diffusion from one binding site to the next.