浒苔dmsp裂解酶l(dddl)基因的克隆与表达分析-cloning and expression analysis of dmsp lyase l ( dddl ) gene in enteromorpha prolifera.docxVIP

浒苔 DMSP 裂解酶 L（dddL）基因的克隆与表达分析英文摘要Molecular Cloning and Expression Analysis of DMSP lyase Gene in Ulva proliferaAbstractDimethylsufide (DMS) is the most abundant volatile biogenic sulfur compound in the surface ocean，which plays an important role in the global sulfur cycle and global climate change. Dimethylsulfoniopropionate (DMSP) is the major precursor of DMS.DMSP can be degraded to DMS and acrylic acid with DMSP cleavage lyase. DMSP is a kind of osmotic substances，mainly in themicroalgae、seagrasses and higher plants in sea water．When a organism containing DMSP is dead，the marine microorganismsdecompose the DMSP into DMS(dimethyl sulfide)and crylic acid by DMS synthase. The DMS overflows from the surface of the ocean into the atmosphere to cause acidrain．Because DMS can form clouds，it decreases the green house effect．DMSP itselfcan promote the nutrition metabolism of mammal、poultry、fish and shrimps. It is shown by enzymatic study that two kinds of S-methyltransferases (E.C.，E.C.) from animals‘ livers can transfer S-methyl from DMSP to metabolism in theorganism．DMSP, the main osmotic matedal in marine plants, comes from Methionine.DMSP lyases exist in different bacterias and also present in some algaes .The DMSP lyase dddL gene of Ulva prolifra was cloned. Firstly, partial dddL DNA sequence was obtained using PCR technology. The results show that the similarity between the obtained partial DNA sequence and the dddL sequence in NCBI is very high. Followed by application of the method of chromosome walking respectively dddL part of the gene sequence 5 upstream sequence and the 3 downstream sequence to be amplified. Finally a cloned sequence was obtained by 5‘RACE technology. The full length of dddL gene of Ulva prolifera and the length of 5 end promoter sequences were obtained on the basis of the three fragment sequences stitching. Open reading frame (ORF) was encoded by 223 amino acids. The molecular weight of deduced protein was 24.74kDa and its