Poole D M, Hazlewood G P, Huskisson N S, Virden R, Gilbert H J
Department of Biological and Nutritional Sciences, University of Newcastle upon Tyne, UK.
FEMS Microbiol Lett. 1993 Jan 1;106(1):77-83. doi: 10.1111/j.1574-6968.1993.tb05938.x.
The five conserved tryptophan residues in the cellulose binding domain of xylanase A from Pseudomonas fluorescens subsp. cellulosa were replaced with alanine and phenylalanine. The mutated domains were fused to mature alkaline phosphatase, and the capacity of the hybrid proteins to bind cellulose was assessed. Alanine substitution of the tryptophan residues, in general, resulted in a significant decrease in the capacity of the cellulose binding domains to bind cellulose. Mutant domains containing phenylalanine substitution retained some affinity for cellulose. The C-terminal proximal tryptophan did not play an important role in ligand binding, while Trp13, Trp34 and Trp38 were essential for the cellulose binding domain to retain cellulose binding capacity. Data presented in this study suggest major differences in the mechanism of cellulose attachment between Pseudomonas and Cellulomonas cellulose binding domains.
荧光假单胞菌纤维素亚种木聚糖酶A的纤维素结合结构域中的五个保守色氨酸残基被丙氨酸和苯丙氨酸取代。将突变的结构域与成熟的碱性磷酸酶融合，并评估杂合蛋白结合纤维素的能力。一般来说，色氨酸残基被丙氨酸取代会导致纤维素结合结构域结合纤维素的能力显著下降。含有苯丙氨酸取代的突变结构域对纤维素仍保留一些亲和力。靠近C端的色氨酸在配体结合中不起重要作用，而Trp13、Trp34和Trp38对于纤维素结合结构域保持纤维素结合能力至关重要。本研究提供的数据表明，假单胞菌和纤维单胞菌纤维素结合结构域在纤维素附着机制上存在重大差异。
