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ツゲ ヒデアキ
TSUGE HIDEAKI
津下 英明 所属 京都産業大学 生命科学部 先端生命科学科 職種 教授 |
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| 言語種別 | 英語 |
| 発行・発表の年月 | 2004 |
| 形態種別 | 研究論文 |
| 査読 | 査読あり |
| 標題 | Amino-acid residues involved in the expression of the activity of Escherichia coli ToIC |
| 執筆形態 | その他 |
| 掲載誌名 | MICROBIOLOGY AND IMMUNOLOGY |
| 出版社・発行元 | CENTER ACADEMIC PUBL JAPAN |
| 巻・号・頁 | 48(10),pp.713-722 |
| 著者・共著者 | H Yamanaka,N Morisada,M Miyano,H Tsuge,S Shinoda,E Takahashi,K Okamoto |
| 概要 | The Escherichia coli TolC, composed of 471 amino-acid residues, functions as a channel tunnel in the transport of various molecules across the outer membrane. We found previously that Leu-412, the 60th amino-acid residue from the carboxy terminal end, was crucial to the transport activity of TolC. Leu-412 is located in a domain which protrudes from the main body of TolC into the periplasm. Subsequent study indicated that the hydrophobicity generated by Leu-412 played an important role in the activity of TolC (H. Yamanaka, T. Nomura, N. Morisada, S. Shinoda, and K. Okamoto, Microb. Pathog. 33: 81-89, 2002). We predicted that other hydrophobic amino-acid residues around Leu-412 were also involved in the expression of the activity of TolC. To test this possibility, we substituted several hydrophobic residues around Leu-412, (Leu-3, Val-6, Leu-212, Leu-213, Leu-223, and Leu-224), with serine and examined the activity of these mutant TolCs. The result showed that Leu-3 is involved in the activity of TolC, but the other residues are not. The involvement of Leu-3 was confirmed by the residue deletion experiment. A subsequent point-mutational analysis of the residue showed that a hydrophobic side chain is required at position 3 for TolC to express its activity. As the distance between the alpha-carbons of Leu-3 and Leu-412 is just 7.45 Angstrom, hydrophobic interaction between the two leucine residues might be involved in the activity of TolC. |
| ISSN | 0385-5600 |