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酿酒酵母中铁载体类铁色素转运蛋白(Arn1p)的鉴定及其底物特异性

Identification and substrate specificity of a ferrichrome-type siderophore transporter (Arn1p) in Saccharomyces cerevisiae.

作者信息

Heymann P, Ernst J F, Winkelmann G

机构信息

Institut für Mikrobiologie and Biotechnologie, Universität Tübingen, Auf der Morgenstelle 28, D-72076, Tübingen, Germany.

出版信息

FEMS Microbiol Lett. 2000 May 15;186(2):221-7. doi: 10.1111/j.1574-6968.2000.tb09108.x.

Abstract

Genes encoding transporters for heterologous siderophores have been identified in Saccharomyces cerevisiae, of which SIT1, TAF1, and ENB1 encode the transporters for ferrioxamines, ferric triacetylfusarinine C and ferric enterobactin, respectively. In the present communication we have shown that a further gene encoding a member of the major facilitator superfamily, ARN1 (YHL040c), is involved in the transport of a specific class of ferrichromes, possessing anhydromevalonyl residues linked to N(delta)-ornithine (ARN). Ferrirubin and ferrirhodin, which both are produced by filamentous fungi, are the most common representatives of this class of ferrichromes. A strain possessing a disruption in the ARN1 gene was unable to transport ferrirubin, ferrirhodin and also ferrichrome A, indicating that the encoded transporter recognizes anhydromevalonyl and the structurally-related methylglutaconyl side-chains surrounding the iron center. Ferrichromes possessing short-chain ornithine-N(delta)-acetyl residues such as ferrichrome, ferricrocin and ferrichrysin, were excluded by the Arn1 transporter. Substitution of the iron-surrounding N-acyl chains of ferrichromes by propionyl residues had no effect, whereas substitution by butyryl residues led to recognition by the Arn1 transporter. This would indicate that a chain length of four C-atoms is sufficient to allow binding. Using different asperchromes (B1, D1) we also found that a minimal number of two anhydromevalonyl residues is sufficient for recognition by Arn1p. Contrary to the iron-surrounding N-acyl residues, the peptide backbone of ferrichromes was not an important determinant for the Arn1 transporter.

摘要

在酿酒酵母中已鉴定出编码异源铁载体转运蛋白的基因,其中SIT1、TAF1和ENB1分别编码铁胺、三乙酰铁载体蛋白C和肠杆菌素的转运蛋白。在本通讯中,我们表明另一个编码主要转运体超家族成员的基因ARN1(YHL040c)参与了一类特定的铁色素的转运,这类铁色素具有与N(δ)-鸟氨酸(ARN)相连的脱水甲戊酰基残基。丝状真菌产生的铁红素和铁红蛋白是这类铁色素最常见的代表。具有ARN1基因破坏的菌株无法转运铁红素、铁红蛋白以及铁色素A,这表明编码的转运蛋白识别铁中心周围的脱水甲戊酰基和结构相关的甲基戊二酰基侧链。具有短链鸟氨酸-N(δ)-乙酰基残基的铁色素,如铁色素、铁菌素和铁黄素,被Arn1转运蛋白排除在外。用丙酰基残基取代铁色素中铁周围的N-酰基链没有影响,而用丁酰基残基取代则导致Arn1转运蛋白的识别。这表明四个碳原子的链长足以允许结合。使用不同的曲霉色素(B1、D1),我们还发现最少两个脱水甲戊酰基残基就足以被Arn1p识别。与铁周围的N-酰基残基相反,铁色素的肽主链对Arn1转运蛋白不是一个重要的决定因素。

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