Suzuki K, Suzuki M, Taiyoji M, Nikaidou N, Watanabe T
Department of Biosystem Science, Graduate School of Science and Technology, Niigata University, Japan.
Biosci Biotechnol Biochem. 1998 Jan;62(1):128-35. doi: 10.1271/bbb.62.128.
A chitin binding protein (CBP21) 21 kDa in size, is a major protein in the culture supernatant when Serratia marcescens 2170 is grown in the presence of chitin. The gene (cbp) for CBP21 was found to be located in a region 1.5 kb downstream of the chiB gene encoding chitinase B. The cbp gene encodes a polypeptide of 197 amino acids with a calculated size of 21.6 kDa containing a putative signal sequence of 27 amino acids. Comparison of the amino acid sequence of the deduced polypeptide with that of other proteins showed that CBP21 is similar (45.3% amino acid identity) to CHB1 of Streptomyces olivaceoviridis. Purified CBP21 prepared from the periplasmic fraction of Escherichia coli carrying the cloned cbp gene showed its highest binding activity to squid chitin (beta-chitin) followed by colloidal chitin and regenerated chitin. Binding of CBP21 to regenerated chitin was affected by pH, in particular, low pH reduced binding activity markedly. The presence of similar chitin binding proteins in the distantly related microorganisms, Streptomyces and Serratia, suggests a wide distribution of this type of chitin binding protein in chitinolytic microorganisms.
一种大小为21 kDa的几丁质结合蛋白（CBP21）是粘质沙雷氏菌2170在几丁质存在下生长时培养上清液中的主要蛋白质。发现CBP21的基因（cbp）位于编码几丁质酶B的chiB基因下游1.5 kb的区域。cbp基因编码一个由197个氨基酸组成的多肽，计算大小为21.6 kDa，包含一个27个氨基酸的推定信号序列。将推导的多肽氨基酸序列与其他蛋白质的氨基酸序列进行比较，结果表明CBP21与橄榄绿链霉菌的CHB1相似（氨基酸同一性为45.3%）。从携带克隆的cbp基因的大肠杆菌周质部分制备的纯化CBP21对鱿鱼几丁质（β-几丁质）的结合活性最高，其次是胶体几丁质和再生几丁质。CBP21与再生几丁质的结合受pH影响，特别是低pH会显著降低结合活性。在远缘相关微生物链霉菌和沙雷氏菌中存在相似的几丁质结合蛋白，这表明这类几丁质结合蛋白在几丁质分解微生物中广泛分布。
