Determination of structure/function relationships of the Escherichia coli mannitol permease by deletion and site-specific mutagenesis
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Abstract
The Escherichia coli mannitol permease (EIIMtl) is a 68 kilodalton (kDa)
membrane-bound protein that carries out phosphoenolpyruvate-dependent transport and
phosphorylation of D-mannitol. This protein also catalyzes a phosphoexchange reaction
between mannitol and mannitol-1-phosphate and acts as a chemotactic receptor for mannitol
in this bacterium. The gene that encodes this protein, mtlA, has been cloned and
sequenced. A structural model for the EIIMtl has been previously proposed based upon
hydropathy analysis of the deduced amino acid sequence of mtlA, proteolysis studies, and
'phoA fusion analysis. According to this model, the N-terminal domain (residues 1-334) is
comprised of six or seven membrane-spanning alpha-helices and the C-terminal domain
(residues 335-637), which contains two phosphorylation sites, is exposed to the
cytoplasm. A series of mtlA deletion mutants was constructed for further analysis of
structure/function relationships in the mannitol permease. In this study, several deletion
mutants are selected for characterization of their mannitol binding activity, insertion/stability
in the membrane, and oligomerization. The results showed that [TRUNCATED]
Description
Thesis (Ph. D.)--Boston University, 1994.
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