Bioinformatics And Expression Analysis Of LHC Genes Cloned From Porphyridium Purpureum

The unicellular red alga,P.purpureum,belongs to Rhodophyta.It can synthesize some specific bioactive substances such as phycobiliprotein and exopolysaccharide,which have become hot spots in the algae application research.Five aspects of P.purpureum are studied in this paper and the results were as follows:(1)aCloning of PpLhc genes.Comparing with the known Lhc gene,five full length Lhc cDNAs were found by screening the sequence database of P.purpureum,and they were named as PpLhc1~PpLhc6.The specific primers were designed according the alignments of the six genes.The full length of PpLhc1~PpLhc6 genes were cloned by PCR.The length of the gene sequences were among 701 ~ 787 bp,the length of predicted ORFs were among582 ~672 bp,the numbers of amino acid encoded by the genes were 193~223.(2)Bioinformatics analysis.Analysis of The deduced proteins showed some features.For example,the physicochemical characteristics of PpLHC1 protein was different from those of the other PpLHC proteins;the PpLHC5 protein was the only one which have membrane spaning domain.The main components of PpLHC1 ~ PpLHC6 in secondary structure are random coil and ?-helix,and the 3D models of the deduced proteins were successfully constructed.Analysis of Phylogenetic tree showed that the PpLHC proteins from P.purpureum did not gathered to any LHC proteins of higher plant and other algae.It implied that the evolution of P.purpureum seems independently.(3)In order to explore changes in PpLhc mRNA expression levels corresponding to different irradiations,the mRNA expression levels were measured by Real-Time Quantitative PCR.The results indicated that the PpLhc mRNA level was significantly affected by light intensity.Fluctuations in the mRNA levels might be controlled by the different roles of the genes in photosynthesis.The works will help further researches on the expression of PpLhc gene family.(4)The expression vector of PpLhc1 and PpLhc4 genes were constructed by fused the genes into Pcold vector and then transfer the expression vector into E.coli Rosetta to express.The target proteins in inclusion body form were obtained.The SDS-PAGE electrophoresises of these fusion proteins indicated that the construction of expression vectors were successfuland the molecular weight were about 24 kD and 26 kD,which were similar to the predicted molecular weight.(5)A strain of bacteria in culture medium of P.purpureum was isolated,which is classified as Stappia indica.Then using the axenic microalgae as a control,the influences of the bacteria on growth of the alga were investigated.The results showed that the strain accelerated the growth and photosynthesis of P.purpureum.