Unity and diversity in active transport in cell membrans

It is important to analyze many transport systems for the investigation of unity and diversity in structure，function and mechanism in active transport proteins。Fortunately，we have found and investigated many active transport systems in bacterial cells so far。In the past two years，we have obtained the following results.1)We analyzed many Na I D1+i D1-coupled transport systems，mainly Na I D 1+I D 1/melibiose symporter and Na I D 1+I D 1/serine symporter of Escherichia coli and some other bacteria.We characterized the symporters from biochemical view point and genetic view point.We established methods for over production，large-scale purification and reconstitution of the Na I D 1+I D 1/melibiose symporter protein and Na I D 1+I D 1/serine symporter protein.This opened up a way for further analysis in structure，function and mechanism an active transport proteins.2)We identified regions and amino acid residues important or necessary for ion-coupling or substrate recognition in the Na I D1+i D1/melibiose symporter protein through mutant analysis and site-directed mutagenesis.Homology search and motif analysis were also useful for such analysis.3)We found new transport systems and cloned their genes in some bacteria.Biochemical and genetic analyses further revealed unity and diversity in transport proteins.Collaborations with Prof.Wilson and Prof.Konings were very valuable foe this project。

It is important to analyze many transport systems for the investigation of unity and diversity in structure, function and mechanism in active transport proteins. Fortunately, we have found and investigated many active transport systems in bacterial cells so far. In the past two years, we have obtained the following results.1) We analyzed many NaィイD1+ィエD1-coupled transport systems, mainly NaィイD1+ィエD1/melibiose symporter and NaィイD1+ィエD1/serine symporter of Escherichia coli and some other bacteria. We characterized the symporters from biochemical view point and genetic view point. We established methods for over production, large-scale purification and reconstitution of the NaィイD1+ィエD1/melibiose symporter protein and NaィイD1+ィエD1/serine symporter protein. This opened up a way for further analysis in structure, function and mechanism an active transport proteins.2) We identified regions and amino acid residues important or necessary for ion-coupling or substrate recognition in the NaィイD1+ィエD1/melibiose symporter protein through mutant analysis and site-directed mutagenesis. Homology search and motif analysis were also useful for such analysis.3) We found new transport systems and cloned their genes in some bacteria. Biochemical and genetic analyses further revealed unity and diversity in transport proteins.Collaborations with Prof. Wilson and Prof. Konings were very valuable foe this project.