Open AccessCharacterization of a DNA fragment carrying the raw starch‐digesting α‐amylase and salt‐dependent α‐amylase genes from Bacillus circulans F‐2
Author(s) -
Kim CheorlHo
Publication year - 1995
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1995.tb07406.x
Subject(s) - bacillus circulans , subcloning , amylase , escherichia coli , microbiology and biotechnology , biochemistry , biology , plasmid , gene , dna , chemistry , enzyme
A 5.4 kb Hind III DNA fragment carrying the gene encoding raw starch‐digesting α‐amylase (RSDA), has been previously cloned from Bacillus circulans F‐2 and expressed in Escherichia coli [Kim et al. (1990) Biochim. Biophys. Acta 1048, 2233–2238]. Interestingly, when the cell extract of E. coli harboring a plasmid carrying this fragment was incubated with l M NaCl, it exhibited about 10 times higher enzyme activity than when assayed without NaCl. Differential zymograms showed two different amylase activities: one for RSDA and the other for a salt‐dependent a‐amylase (SDA). Even though RSDA activity was detected without NaCl, SDA activity was detected only in high concentrations of NaCl. SDA activity was fully detected at above l M NaCl. Results from subcloning of the genes, fractionation analysis of cell extracts, and immunological assays clearly suggested that the two amylases are genetically distinct and that genes for both enzymes are closely linked on the 5.4 kb DNA fragment.