Structural evidence that the 32-kilodalton lipoprotein (Tp32) of Treponema pallidum is an L-methionine-binding protein.
A structure-to-function approach was undertaken to gain insights into the potential function of the 32-kDa membrane lipoprotein (Tp32) of Treponema pallidum, the syphilis bacterium. The crystal structure of rTp32 (determined at a resolution of 1.85 A) shows that the organization of rTp32 is similar to other periplasmic ligand-binding proteins (PLBPs), in that it consists of two alpha/beta domains, linked by two crossovers, with a binding pocket between them. In the pocket, a molecule of L-methionine was detected in the electron density map. Residues from both domains interact with the ligand. One of the crossover regions is comprised of a 3(10)-helix, a feature not typical in other ligand-binding proteins. Sequence comparison shows strong similarity to other hypothetical methionine-binding proteins. Together, the data support the notion that rTp32 is a component of a periplasmic methionine uptake transporter system in T. pallidum.
Department of Microbiology, University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA.
Ranjit K
RK
Deka
Lori
L
Neil
Kayla E
KE
Hagman
Mischa
M
Machius
Diana R
DR
Tomchick
Chad A
CA
Brautigam
Michael V
MV
Norgard
D001053:Apolipoproteins / Q000737:chemistry; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000502:physiology*; D018360:Crystallography, X-Ray; D004583:Electrons; D004926:Escherichia coli / Q000378:metabolism; D008024:Ligands; D008074:Lipoproteins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry* / Q000502:physiology*; D008715:Methionine / Q000737:chemistry*; D008958:Models, Molecular; D015233:Models, Statistical; D019897:Periplasm / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D014210:Treponema pallidum / Q000378:metabolism*
D001053:Apolipoproteins; D002352:Carrier Proteins; D008024:Ligands; D008074:Lipoproteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; C496546:Tp32 protein, Treponema pallidum; D008715:Methionine