Molecular Cloning Of Maltooligosyltrehalose Trehalohydrolase Gene From Nostoc Flagelliforme And Relative Response To Stresses

Nostoc flaglliforme which distributed in west and northwest of China widely is one of valuable terrigenous cyanobacterias. Its'living envioroment is extremely atrocious.A genomic DNA fragment encoding a putative maltooligosyltrehalose trehalohydrolase (NfMTH) for trehalose biosynthesis was cloned by the degenerate primer-PCR from cyanobacterium Nostoc flagelliforme. The ORF of NfMTH is 1,848 bp in length and encodes 615 amino acid residues constituting a 70 kDa protein.The deduced amino acid sequence of NfMTH contains 4 regions highly conserved for MTHs. By expression of NfMTH in E. coli, the function of this protein was demonstrated that the recombinant protein catalyzed the hydrolysis of maltooligosyl trehalose to trehalose. The expressions of NfMTH and NfMTS in the filaments of N. flagelliforme were upregulated significantly under dehydration stress, NaCl stress. The accumulations of both trehalose and sucrose in the filaments of N. flagelliforme were also improved significantly but in low levels under above stresses, indicating that both trehalose and sucrose did not work as"chemical chaperones"for protection of macromolecules against stresses.The results show that the TreZ from Nostoc. flaglliforme was cloned successfully and this work provided a theoretical and experimental basis for further study of trehalose metabolism in Nostoc flaglliforme response to stress resistance mechanism.