Comparison of expression and enzymatic properties of Aspergillus oryzae lysine aminopeptidases ApsA and ApsB.
The apsA and apsB genes encoding family M1 aminopeptidases were identified in the industrial fungus Aspergillus oryzae. The apsB was transcriptionally up-regulated up to 2.5-fold in response to the deprivation of nitrogen or carbon sources in growth media, while up-regulation of apsA was less significant. The encoded proteins were bacterially expressed and purified to characterize their enzymatic properties. ApsA and ApsB were optimally active at pH 7.0 and 35 °C and stable at pH ranges of 6-10 and 4-10, respectively, up to 40 °C. The enzymes were inhibited by bestatin and EDTA, as has been reported for family M1 aminopeptidases that characteristically contain a zinc-binding catalytic motif. Both enzymes preferentially liberated N-terminal lysine, which is an essential amino acid and an important additive to animal feed. Enzymes that efficiently release N-terminal lysine from peptides could be useful for food and forage industries. Examination of the reactivity toward peptide substrate of varying length revealed that ApsB exhibited broader substrate specificity than ApsA although the reactivity of ApsB decreased as the length of peptide substrate decreased.
Applied Microbiology Division, NARO, National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki, 305-8642, Japan.
Junichiro
J
Marui
Mayumi
M
Matsushita-Morita
Sawaki
S
Tada
Ryota
R
Hattori
Satoshi
S
Suzuki
Hitoshi
H
Amano
Hiroki
H
Ishida
Youhei
Y
Yamagata
Michio
M
Takeuchi
Ken-Ichi
K
Kusumoto
D000626:Aminopeptidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001236:Aspergillus oryzae / Q000201:enzymology* / Q000235:genetics*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
D005656:Fungal Proteins; D007527:Isoenzymes; D011994:Recombinant Proteins; D000626:Aminopeptidases; C056860:lysyl aminopeptidase