Physicochemical Evidence that Treponema pallidum TroA Is a Zinc-Containing Metalloprotein That Lacks Porin-Like Structure
| Autor: | Justin D. Radolf, Yong Hwan Lee, Michael V. Norgard, Kayla E. Hagman, Ranjit K. Deka, Dmitriy V. Shevchenko, Charles A. Hasemann, Clifford A. Lingwood |
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| Jazyk: | angličtina |
| Rok vydání: | 1999 |
| Předmět: |
Signal peptide
Circular dichroism Octoxynol Porins Biology Microbiology Polyethylene Glycols Bacterial Proteins Metalloproteins Metalloprotein Treponema pallidum Molecular Biology chemistry.chemical_classification Treponema Circular Dichroism Spectrophotometry Atomic Spectrometry X-Ray Emission Periplasmic space biology.organism_classification Enzymes and Proteins General bacterial porin family Zinc chemistry Biochemistry Porin Bacterial outer membrane |
| Popis: | Although TroA (Tromp1) was initially reported to be a Treponema pallidum outer membrane protein with porin-like properties, subsequent studies have suggested that it actually is a periplasmic substrate-binding protein involved in the transport of metals across the treponemal cytoplasmic membrane. Here we conducted additional physicochemical studies to address the divergent viewpoints concerning this protein. Triton X-114 phase partitioning of recombinant TroA constructs with or without a signal sequence corroborated our prior contention that the native protein’s amphiphilic behavior is due to its uncleaved leader peptide. Whereas typical porins are trimers with extensive β-barrel structure, size exclusion chromatography and circular dichroism spectroscopy revealed that TroA was a monomer and predominantly alpha-helical. Neutron activation, atomic absorption spectroscopy, and anomalous X-ray scattering all demonstrated that TroA binds zinc in a 1:1 molar stoichiometric ratio. TroA does not appear to possess structural features consistent with those of bacterial porins. |
| Databáze: | OpenAIRE |
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