Isolation, Characterization And Genomic Analysis Of Meiothermus Myoviridae Phage MMP17 From Eryuan Hot Spring, Yunnan, China

Viruses are extrordinarily important because of their roles in processes of evolution and flow of matter and energy in ecological system. With the rapid development of bioinformatics and genomics, an increasing lines of evidences show that viruses play an essential part in horizontal gene transfer among different species.High temperature ecological system is of great interest because of its special biological property and evolutionary degrees. Thermus spp is one of the ancient genuses of thermophilic bacteria, and is studied in physiology as a model for thermophiles. Meiothermus spp is later reclassified as a separate genus from Genus Thermus.In this study, a new thermophilic bacteriophage named MMP17 (Meiothermus Myoviridae phage 17) was isolated from eryuan hot spring and its genomic sequence was checked and analyzed.MMP17 is a typical myovirus, which belongs to caudaevirus, with an icosahedral head (42 nm in diameter) and a tail (120 nm in length and 17 nm in width). MMP17 was very stable at 55-60℃and pH 6-7. MMP17 is double-stranded DNA virus. The genome of MMP17 is 33172 bp, with less than 6000 bp DNA redundant. The C+G content of MMP17 genome was 63.86%, and about 86 ORFs (open reading frame) was found. None of ORFs, which is related to the life cycle activities of phage, was found in positive-sense strand. All of them located in antisense strand. According to the different life activities, MMP17 genome was divided into two gene regions. One is gene regions of early phase, which include a large number of genes of MMP17 DNA replication. Another one is gene regions of late phase, which include the structural protein and assembly protein of MMP17. According to the results of mass spectrometric identification, two structural proteins with estimated molecular masses of 31 and 50 kDa, respectively were identified. One is major head protein. Another one is a new structural protein. The results of homologous protein analysis show that a lot of functional proteins of MMP17 have high homology with Thermus, Meiothermus and some mesophilic bacteria. While some functional proteins of MMP17 have certain homology with mesophilic bacteria, homology is far below the Thermus and Meiothermus. In this work, the first Meiothermus phage MMP17 was isolated and characterized, and its genomic sequence was checked and analyzed. It will be laying the foundations for studing the interaction between Meiothermus and their phages and heat tolerance mechanisms.