Membrane topology of Escherichia coli diacylglycerol kinase.
AUTOR(ES)
Smith, R L
RESUMO
The topology of Escherichia coli diacylglycerol kinase (DAGK) within the cytoplasmic membrane was elucidated by a combined approach involving both multiple aligned sequence analysis and fusion protein experiments. Hydropathy plots of the five prokaryotic DAGK sequences available were uniform in their prediction of three transmembrane segments. The hydropathy predictions were experimentally tested genetically by fusing C-terminal deletion derivatives of DAGK to beta-lactamase and beta-galactosidase. Following expression, the enzymatic activities of the chimeric proteins were measured and used to determine the cellular location of the fusion junction. These studies confirmed the hydropathy predictions for DAGK with respect to the number and approximate sequence locations of the transmembrane segments. Further analysis of the aligned DAGK sequences detected probable alpha-helical N-terminal capping motifs and two amphipathic alpha-helices within the enzyme. The combined fusion and sequence data indicate that DAGK is a polytopic integral membrane protein with three transmembrane segments with the N terminus of the protein in the cytoplasm, the C terminus in the periplasmic space, and two amphipathic helices near the cytoplasmic surface.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=196734Documentos Relacionados
- Cytosolic rat brain synapsin I is a diacylglycerol kinase.
- Membrane topology of the Escherichia coli ExbD protein.
- Escherichia coli diacylglycerol kinase: a case study in the application of solution NMR methods to an integral membrane protein.
- Topology of the lac carrier protein in the membrane of Escherichia coli.
- lac permease of Escherichia coli: topology and sequence elements promoting membrane insertion.