Exploration And Function Analysis Of LysM Domain Genes In Archaea

The LysM domain plays an important role in identifying pathogen invasion and stimulating plant immune defense.At present,a large number of LysM domain genes have been identified from prokaryotes and eukaryotes genomes,but it have not been found in Archaea so far.With the rapid development of high-throughput sequencing in recent years,a large numbers of archaeal genome have been sequenced.Is there an LysM domain gene in archaeal genome? If so,does its function related to plant immune defense? Based on these questions,the archaeal genome sequence information were collected from the public databases,and the LysM domain genes were excavated in the archaea genome.After the phylogenetic analysis,a representative archaeal LysM domain gene was selected to study the functional activities of LysM domain protein by prokaryotic expression.Additionally,heterogenous expression of this gene in the functional deletion mutant of LysM domain in Arabidopsis was used to explore the functional characteristics in fungal pathogen identification to induce plant immune response.The study of LysM domain genes of archaea has important theoretical significance for the origin of LysM gene in plants,and also has potential application value in crop resistance breeding.The main results are as follows:1.The 441 non-redundant archaeal genomic sequences were downloaded from the NCBI and Ensembl Bacteria databases.The functional domain analysis were performed,and the LysM domains were identified from 27 kinds of archaea,which confirming that LysM domains also existed in archaea.2.Based on the classification information of these archaeas and the amino acid sequence information of the identified LysM domain proteins,it was concluded that the LysM domain of archaea is mainly existed in Euryarchaeota,and the LysM domain is mainly located in the C-terminus of the sequence.3.The LysM domain gene of Halobiforma_nitratireducens(HnLysM)was used to construct the prokaryotic expression vector.The protein purification was performed after western blot.The polysaccharide binding experiment showed that the recombinant protein had the chitin specific binding activity,but the enzyme activity analysis showed that it did not have chitinase activity.4.The plant expression vector of HnLysM was constructed,and then was ectopic expressed in the functional deletion mutant of LysM domain in Arabidopsis.TheHelminthosporium maydis infection experimental results showed that there was no significant difference between the mutants and transgenic plants,indicating that HnLysM could not restore the immune response function of the chitin triggered by AtCERK1.This study preliminarily suggested that the functions of the LysM domain gene in archaea are completely different from the chitinase function in fungal and the identification of pathogenic to induce plant immune function in plants.The special functions of LysM domain gene in archaea need further analysis.