Sueda Shinji, Li Yan-Qiu, Kondo Hiroki, Kawarabayasi Yutaka
Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Kawazu 680-4, Iizuka 820-8502, Japan.
Biochem Biophys Res Commun. 2006 May 26;344(1):155-9. doi: 10.1016/j.bbrc.2006.03.118. Epub 2006 Apr 17.
Biotin protein ligase (BPL) is an enzyme mediating biotinylation of a specific lysine residue of the carboxyl carrier protein (BCCP) of biotin-dependent enzymes. We recently found that the substrate specificity of BPL from archaeon Sulfolobus tokodaii is totally different from those of many other organisms, in reflection of a difference in the local sequence of BCCP surrounding the canonical lysine residue. There is a conserved glycine residue in the biotin-binding site of Escherichia coli BPL, but this residue is replaced with alanine in S. tokodaii BPL. To test the notion that this substitution dictates the substrate specificity of the latter enzyme, this residue, Ala-43, was converted to glycine. The K(m) values of the resulting mutant, A43G, for substrates, were smaller than those of the wild type, suggesting that the residue in position 43 of BPL plays an important role in substrate binding.
生物素蛋白连接酶（BPL）是一种介导生物素依赖性酶的羧基载体蛋白（BCCP）特定赖氨酸残基生物素化的酶。我们最近发现，嗜热栖热菌（Sulfolobus tokodaii）的BPL底物特异性与许多其他生物的底物特异性完全不同，这反映了围绕典型赖氨酸残基的BCCP局部序列的差异。大肠杆菌BPL的生物素结合位点存在一个保守的甘氨酸残基，但在嗜热栖热菌BPL中该残基被丙氨酸取代。为了验证这种取代决定了后一种酶的底物特异性这一观点，将该残基Ala-43转换为甘氨酸。所得突变体A43G对底物的K(m)值小于野生型，表明BPL第43位的残基在底物结合中起重要作用。
