Submitted to: Society of Industrial Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/29/2004
Publication Date: 7/29/2004
Citation: Mertens, J.A., Skory, C.D. 2004. Discovery and characterization of a second glucoamylase gene in rhizopus oryzae [abstract]. Society of Industrial Microbiology. p. 96.
Technical Abstract: Rhizopus oryzae has long been used for glucoamylase production for fermentation applications. Previous descriptions have suggested that this fungus has a single glucoamylase gene, amyA, and that multiple forms of the enzyme result from limited proteolysis of the N-terminus. However, we have recently identified a second glucoamylase gene, amyB, that appears to code for one of these isozymes. The existence of amyB was confirmed by Southern blot analysis, molecular cloning, and sequencing. Sequence analysis of this amyB genomic clone reveals extensive homology with the amyA in the 1.5-kb coding region, as well as, the flanking ends. A notable difference is that the amyB does not encode a starch binding domain and also contains a 24 bp insertion near the 3' end of the open reading frame. In addition, isolation of an amyB cDNA clone demonstrates identical intron splicing as compared with amyA and codes for a putative 52.4 kD enzyme. Amino acid identity between the two putative proteins, excluding the starch binding domain, was over 91%. Expression analysis of amyB in Rhizopus when cultured with different carbon sources has been performed utilizing northern blotting and real-time PCR will be discussed.