海洋链霉菌酮合成酶结构域基因的克隆及分析

海洋链霉菌通过聚酮合酶(PKS)合成许多结构和功能多样且具有药用价值的聚酮化合物(PKs),酮合成酶结构域(KS)作为PKS的核心结构域，可催化底物与伸长的聚酮之间的脱羧缩合，在聚酮化合物生物合成中起着重要作用。本文通过对从海洋链霉菌Streptomyces sp. X66基因组DNA克隆获得的ks基因的生物信息学分析表明，该ks基因序列长945 bp, BLAST序列比对显示其具有典型的酮合酶结构域的功能区域。理化分析显示其拟编码309个氨基酸，理论等电点为6.60,原子组成为C₁₄₀₁H₂₂₃₉N₄₂₅O₄₁₉S₈,不稳定指数为42.11,平均亲水系数为0.112,编码产物为酸性疏水不稳定蛋白，且不含信号肽和跨膜结构，二级结构以无规则卷曲和α-螺旋为主，SDS-PAGE显示其分子量约为55 kDa。通过对ks基因的研究，为进一步解析聚酮化合物合成代谢中的调控机制及组合生物学和体外酶系合成聚酮化合物提供参考。

Cloning and Analysis of Ketone Synthase Domain Gene from Marine Streptomyces

Marine Streptomyces can synthesize many polyketides (PKs) with medicinal value and diverse structures and functions by polyketide synthase (PKS). The ketone synthase domain (KS), as one of the core domain in PKS, can catalyzes the decarboxylation condensation between substrates and elongated polyketones, and plays an important role in polyketide biosynthesis. In this paper, one ks gene was cloned from Streptomyces sp. X66 genomic DNA, bioinformatic analysis showed that the gene sequence was 945 bp. Blast sequence comparison showed that it had a typical functional region of the ketosynthase domain. Physio-chemical analysis showed that it was intended to encode 309 amino acids, its theoretical isoelectric point was 6.60. The atomic composition was C₁₄₀₁H₂₂₃₉N₄₂₅O₄₁₉S₈ the instability coefficient was 42.11, with average hydrophilicity at 0.112, it encoded an acidic hydrophobic unstable protein without signal peptide and transmembrane structure, and its secondary structure was mainly random coil and α-helix. Its SDS-PAGE showed that its molecular weight was about 55 kDa, which was consistent with the expected. It will provide a scientific basis for further analysis of the regulatory mechanism in the synthesis and metabolism of polyketide compounds, and the synthesis of polyketide compounds by combinatorial biology and in vitro enzymes.