摘要
大多数二型聚羟基脂肪酸酯(Polyhydroxyalkanoates,PHA)合成酶(PhaC)发现于假单胞菌中,其基因组成形式为两个PhaC基因中间有一个PHA降解酶PhaZ基因.根据已知的假单胞菌PHA合成酶基因区域的特殊结构,设计了采用PCR方法从假单胞菌中克隆PHA合成酶基因的克隆方案,并成功地对一株硝基还原假单胞菌(Pseudomonasnitroreducens)和一株石竹伯克霍尔德氏菌(Burkholderiacaryophylli)中的PHA合成酶基因进行了克隆.将克隆得到的phaC1,phaZ和phaC23个基因所编码的氨基酸序列与其他6株已知PHA合成酶基因的假单胞菌的相应序列进行比较,发现这3个蛋白质在假单胞菌中的相似性很高,由phaC1,phaZ和phaC23个基因所组成的基因区域在假单胞菌中非常保守.从对PhaC1,PhaZ和PhaC2的系统进化树分析可以发现,这3个蛋白质与整个PHA合成酶基因区域的系统进化树有着一致的结构.这表明假单胞菌中的PHA合成酶基因区域可能起源于共同的祖先,而其形成可能经历了一次PHA合成酶基因加倍的过程.
Most type II polyhydroxyalkanoate (PHA) synthases (PhaC) were found in Pseudomonas strains, and their genes are colocalized with PHA depolymerase (PhaZ) genes. Recently, two similar PHA biosynthesis gene clusters were cloned and analyzed from Pseudomonas nitroreducens and Burkholderia caryophylli in our lab. The deduced amino acid sequences of the three genes (phaC1, phaZ and phaC2) in the clusters were compared with those from six other Pseudomonas strains (Pseudomonas sp. 613, P. aeruginosa, P. aureofaciens, P. oleovorans, P. putida and P. resinovorans) containing the homologous pha clusters. The results showed that the three proteins PhaC1, PhaZ and PhaC2 shared high similarity. The pha clusters were conserved in the eight strains. The phylogenetic trees for PhaC1, PhaZ and PhaC2 of the eight strains were compared and same topology as that of the whole pha clusters (phaC1phaZphaC2 DNA sequence) from the eight strains was found. This result implied that the pha cluster in Pseudomonas spp. may arise from same ancestor. An ancient duplication event of PHA synthase genes to form the pha cluster may happen earlier than Pseudomonas strains. A hypothetical evolution history was proposed based on the analysis.
出处
《无锡轻工大学学报（食品与生物技术）》
CSCD
北大核心
2002年第6期549-553,共5页
Journal of Wuxi University of Light Industry
基金
国家自然科学基金(30170017)
清华大学985基金资助课题.
